diff --git a/src/diffpy/pdfgui/control/calculation.py b/src/diffpy/pdfgui/control/calculation.py
index 13819b81..ec6928f9 100644
--- a/src/diffpy/pdfgui/control/calculation.py
+++ b/src/diffpy/pdfgui/control/calculation.py
@@ -18,10 +18,11 @@
 
 import copy
 import math
+import pickle
 
 from diffpy.pdfgui.control.controlerrors import ControlConfigError, ControlKeyError, ControlValueError
 from diffpy.pdfgui.control.pdfcomponent import PDFComponent
-from diffpy.pdfgui.utils import pickle_loads, safeCPickleDumps
+from diffpy.pdfgui.utils import safeCPickleDumps
 
 
 class Calculation(PDFComponent):
@@ -253,7 +254,7 @@ def load(self, z, subpath):
 
         returns a tree of internal hierachy
         """
-        config = pickle_loads(z.read(subpath + "config"))
+        config = pickle.loads(z.read(subpath + "config"), encoding="latin1")
         self.rmin = config["rmin"]
         self.rstep = config["rstep"]
         self.rmax = config["rmax"]
diff --git a/src/diffpy/pdfgui/control/fitdataset.py b/src/diffpy/pdfgui/control/fitdataset.py
index eb3d6a80..45a0e8e1 100644
--- a/src/diffpy/pdfgui/control/fitdataset.py
+++ b/src/diffpy/pdfgui/control/fitdataset.py
@@ -461,7 +461,9 @@ def load(self, z, subpath):
         z       -- zipped project file
         subpath -- path to its own storage within project file
         """
-        from diffpy.pdfgui.utils import asunicode, pickle_loads
+        import pickle
+
+        from diffpy.pdfgui.utils import asunicode
 
         self.clear()
         subs = subpath.split("/")
@@ -471,7 +473,7 @@ def load(self, z, subpath):
         self.readObsStr(obsdata)
 
         # data from calculation
-        content = pickle_loads(z.read(subpath + "calc"))
+        content = pickle.loads(z.read(subpath + "calc"), encoding="latin1")
         for item in FitDataSet.persistentItems:
             # skip items which are not in the project file
             if item not in content:
diff --git a/src/diffpy/pdfgui/control/fitting.py b/src/diffpy/pdfgui/control/fitting.py
index 0d56df89..0c534c8f 100644
--- a/src/diffpy/pdfgui/control/fitting.py
+++ b/src/diffpy/pdfgui/control/fitting.py
@@ -15,12 +15,13 @@
 
 from __future__ import print_function
 
+import pickle
 import threading
 import time
 
 from diffpy.pdfgui.control.controlerrors import ControlError, ControlStatusError, ControlValueError
 from diffpy.pdfgui.control.organizer import Organizer
-from diffpy.pdfgui.utils import pickle_loads, safeCPickleDumps
+from diffpy.pdfgui.utils import safeCPickleDumps
 
 # helper routines to deal with PDFfit2 exceptions
 
@@ -210,9 +211,11 @@ def load(self, z, subpath):
 
             self.parameters = CtrlUnpickler.loads(z.read(subpath + "parameters"))
         if "steps" in rootDict:
-            self.itemIndex, self.dataNameDict, self.snapshots = pickle_loads(z.read(subpath + "steps"))
+            self.itemIndex, self.dataNameDict, self.snapshots = pickle.loads(
+                z.read(subpath + "steps"), encoding="latin1"
+            )
         if "result" in rootDict:
-            self.rw, self.res = pickle_loads(z.read(subpath + "result"))
+            self.rw, self.res = pickle.loads(z.read(subpath + "result"), encoding="latin1")
 
         return Organizer.load(self, z, subpath)
 
diff --git a/src/diffpy/pdfgui/control/organizer.py b/src/diffpy/pdfgui/control/organizer.py
index e5c74d37..d44dfb41 100644
--- a/src/diffpy/pdfgui/control/organizer.py
+++ b/src/diffpy/pdfgui/control/organizer.py
@@ -160,25 +160,25 @@ def load(self, z, subpath):
         returns a tree of internal hierachy
         """
         # subpath = projName/myName/
-        from diffpy.pdfgui.utils import unquote_plain
+        from urllib.parse import unquote_plus
 
         subs = subpath.split("/")
         rootDict = z.fileTree[subs[0]][subs[1]]
         if "structure" in rootDict:
             for strucName in rootDict["structure"].keys():
-                struc = FitStructure(unquote_plain(strucName))
+                struc = FitStructure(unquote_plus(strucName))
                 struc.load(z, subpath + "structure/" + strucName + "/")
                 self.add(struc)
 
         if "dataset" in rootDict:
             for datasetName in rootDict["dataset"].keys():
-                dataset = FitDataSet(unquote_plain(datasetName))
+                dataset = FitDataSet(unquote_plus(datasetName))
                 dataset.load(z, subpath + "dataset/" + datasetName + "/")
                 self.add(dataset)
 
         if "calculation" in rootDict:
             for calcName in rootDict["calculation"].keys():
-                calc = Calculation(unquote_plain(calcName))
+                calc = Calculation(unquote_plus(calcName))
                 calc.load(z, subpath + "calculation/" + calcName + "/")
                 self.add(calc)
 
@@ -193,14 +193,14 @@ def save(self, z, subpath):
         subpath -- path to its own storage within project file
         """
         # strucs and datasets
-        from diffpy.pdfgui.utils import quote_plain
+        from urllib.parse import quote_plus
 
         for struc in self.strucs:
-            struc.save(z, subpath + "structure/" + quote_plain(struc.name) + "/")
+            struc.save(z, subpath + "structure/" + quote_plus(struc.name) + "/")
         for dataset in self.datasets:
-            dataset.save(z, subpath + "dataset/" + quote_plain(dataset.name) + "/")
+            dataset.save(z, subpath + "dataset/" + quote_plus(dataset.name) + "/")
         for calc in self.calcs:
-            calc.save(z, subpath + "calculation/" + quote_plain(calc.name) + "/")
+            calc.save(z, subpath + "calculation/" + quote_plus(calc.name) + "/")
         return
 
     def copy(self, other=None):
diff --git a/src/diffpy/pdfgui/control/parameter.py b/src/diffpy/pdfgui/control/parameter.py
index cf8bbe94..06e89b02 100644
--- a/src/diffpy/pdfgui/control/parameter.py
+++ b/src/diffpy/pdfgui/control/parameter.py
@@ -17,8 +17,6 @@
 To be stored in Fitting.parameters { idx : parameter } dictionary
 """
 
-import six
-
 from diffpy.pdfgui.control.controlerrors import (
     ControlError,
     ControlKeyError,
@@ -79,7 +77,7 @@ def setInitial(self, initial):
         if isinstance(initial, Fitting):
             self.__initial = "=" + initial.name
             self.__fitrepr = repr(initial)
-        elif isinstance(initial, six.string_types) and initial[:1] == "=":
+        elif isinstance(initial, str) and initial[:1] == "=":
             self.__initial = initial
             self.__findLinkedFitting()
         else:
diff --git a/src/diffpy/pdfgui/control/pdfguicontrol.py b/src/diffpy/pdfgui/control/pdfguicontrol.py
index f7d480f5..87f3b39d 100644
--- a/src/diffpy/pdfgui/control/pdfguicontrol.py
+++ b/src/diffpy/pdfgui/control/pdfguicontrol.py
@@ -15,13 +15,13 @@
 
 from __future__ import print_function
 
+import io
 import os
+import pickle
 import sys
 import threading
 import time
-
-import six
-import six.moves.cPickle as pickle
+from urllib.parse import quote_plus
 
 from diffpy.pdfgui.control.calculation import Calculation
 from diffpy.pdfgui.control.controlerrors import ControlError, ControlFileError, ControlTypeError
@@ -30,7 +30,7 @@
 from diffpy.pdfgui.control.fitting import Fitting
 from diffpy.pdfgui.control.organizer import Organizer
 from diffpy.pdfgui.control.pdflist import PDFList
-from diffpy.pdfgui.utils import asunicode, quote_plain
+from diffpy.pdfgui.utils import asunicode
 
 
 class PDFGuiControl:
@@ -395,7 +395,7 @@ def _nameParser(namelist):
                     continue
                 fit = Fitting(name)
                 # fitting name stored in rootDict should be quoted
-                rdname = quote_plain(name)
+                rdname = quote_plus(name)
                 # but let's also handle old project files
                 if rdname not in rootDict:
                     rdname = name
@@ -450,7 +450,7 @@ def save(self, projfile=None):
             # fits also contain calculations
             for fit in self.fits:
                 name = fit.name
-                fit.save(z, projName + "/" + quote_plain(fit.name) + "/")
+                fit.save(z, projName + "/" + quote_plus(fit.name) + "/")
                 fitnames.append(name)
             if self.journal:
                 z.writestr(projName + "/journal", asunicode(self.journal))
@@ -516,7 +516,7 @@ def redirectStdout(self):
         from diffpy.pdffit2 import output, redirect_stdout
 
         if output.stdout is sys.stdout:
-            redirect_stdout(six.StringIO())
+            redirect_stdout(io.StringIO())
         return
 
     def getEngineOutput(self):
@@ -525,7 +525,7 @@ def getEngineOutput(self):
 
         txt = output.stdout.getvalue()
         output.stdout.close()
-        redirect_stdout(six.StringIO())
+        redirect_stdout(io.StringIO())
         return txt
 
 
@@ -571,7 +571,7 @@ def loads(s):
             missedModule = str(err).split(" ")[-1]
             if missedModule.find("pdfgui.control") == -1:
                 raise err
-            f = six.StringIO(s)
+            f = io.StringIO(s)
             unpickler = pickle.Unpickler(f)
             unpickler.find_global = _find_global
             return unpickler.load()
diff --git a/src/diffpy/pdfgui/gui/adddatapanel.py b/src/diffpy/pdfgui/gui/adddatapanel.py
index 15cb48ca..6e9ff4ae 100644
--- a/src/diffpy/pdfgui/gui/adddatapanel.py
+++ b/src/diffpy/pdfgui/gui/adddatapanel.py
@@ -106,7 +106,7 @@ def readConfiguration(self):
 
         if remember:
             if self.cP.has_option("DATASET", "last"):
-                self.fullpath = self.cP.getquoted("DATASET", "last")
+                self.fullpath = self.cP.get("DATASET", "last")
                 import os.path
 
                 if not os.path.exists(self.fullpath):
@@ -119,7 +119,7 @@ def updateConfiguration(self):
         """Update the configuration for the 'DATASET'."""
         if not self.cP.has_section("DATASET"):
             self.cP.add_section("DATASET")
-        self.cP.setquoted("DATASET", "last", self.fullpath)
+        self.cP.set("DATASET", "last", self.fullpath)
         return
 
     # EVENT CODE ####
diff --git a/src/diffpy/pdfgui/gui/addphasepanel.py b/src/diffpy/pdfgui/gui/addphasepanel.py
index cc8bbdd3..20e6cce6 100644
--- a/src/diffpy/pdfgui/gui/addphasepanel.py
+++ b/src/diffpy/pdfgui/gui/addphasepanel.py
@@ -128,7 +128,7 @@ def readConfiguration(self):
 
         if remember:
             if self.cP.has_option("PHASE", "last"):
-                self.fullpath = self.cP.getquoted("PHASE", "last")
+                self.fullpath = self.cP.get("PHASE", "last")
                 import os.path
 
                 if not os.path.exists(self.fullpath):
@@ -141,7 +141,7 @@ def updateConfiguration(self):
         """Update the configuration for the 'DATASET'."""
         if not self.cP.has_section("PHASE"):
             self.cP.add_section("PHASE")
-        self.cP.setquoted("PHASE", "last", self.fullpath)
+        self.cP.set("PHASE", "last", self.fullpath)
         return
 
     # EVENT CODE ####
diff --git a/src/diffpy/pdfgui/gui/errorreportdialog.py b/src/diffpy/pdfgui/gui/errorreportdialog.py
index 308954c0..1eea082e 100644
--- a/src/diffpy/pdfgui/gui/errorreportdialog.py
+++ b/src/diffpy/pdfgui/gui/errorreportdialog.py
@@ -151,7 +151,7 @@ def onGoogle(self, event):  # wxGlade: ErrorReportDialog.<event_handler>
         Search for path-independent module and function names and for
         error message extracted from exception traceback.
         """
-        from six.moves.urllib.parse import quote_plus
+        from urllib.parse import quote_plus
 
         traceback = self.text_ctrl_log.GetValue()
         terms = _extractSearchTerms(traceback)
diff --git a/src/diffpy/pdfgui/gui/fittree.py b/src/diffpy/pdfgui/gui/fittree.py
index 250656e3..afd0fcc8 100644
--- a/src/diffpy/pdfgui/gui/fittree.py
+++ b/src/diffpy/pdfgui/gui/fittree.py
@@ -23,6 +23,7 @@
 """
 
 import base64
+import pickle
 import re
 
 import wx
@@ -31,7 +32,7 @@
 from diffpy.pdfgui.control.fitting import Fitting
 from diffpy.pdfgui.gui.pdfguiglobals import iconpath
 from diffpy.pdfgui.gui.wxextensions import wx12
-from diffpy.pdfgui.utils import pickle_loads, safeCPickleDumps
+from diffpy.pdfgui.utils import safeCPickleDumps
 
 
 class FitTree(wx12.TreeCtrl):
@@ -610,7 +611,7 @@ def GetClipboard(self):
 
             if cdatabytes[:16] == "pdfgui_cliboard=".encode():
                 cdatabytes = cdatabytes[16:]
-                cdata = pickle_loads(cdatabytes)
+                cdata = pickle.loads(cdatabytes, encoding="latin1")
         except Exception:
             pass
         return cdata
diff --git a/src/diffpy/pdfgui/gui/mainframe.py b/src/diffpy/pdfgui/gui/mainframe.py
index bbe63bca..1e96261a 100644
--- a/src/diffpy/pdfgui/gui/mainframe.py
+++ b/src/diffpy/pdfgui/gui/mainframe.py
@@ -18,6 +18,7 @@
 """This module contains the main window of PDFgui."""
 
 import os.path
+from configparser import ConfigParser
 
 import wx
 import wx.aui
@@ -48,7 +49,6 @@
 from diffpy.pdfgui.gui.temperatureseriespanel import TemperatureSeriesPanel
 from diffpy.pdfgui.gui.welcomepanel import WelcomePanel
 from diffpy.pdfgui.gui.wxextensions import wx12
-from diffpy.pdfgui.utils import QuotedConfigParser
 
 (PDFCustomEvent, EVT_PDFCUSTOM) = wx.lib.newevent.NewEvent()
 
@@ -300,9 +300,9 @@ def __customProperties(self):
         self.runningDict = {}
 
         # The configuration parser for getting configuration data.
-        # self.cP = QuotedConfigParser()
+        # self.cP = Configparser()
         # Long try this to avoid DuplicateSectionError and ParsingError
-        self.cP = QuotedConfigParser(strict=False, allow_no_value=True)
+        self.cP = ConfigParser(strict=False, allow_no_value=True, interpolation=None)
 
         # Set the program mode
         self.mode = "fitting"
@@ -984,7 +984,7 @@ def loadConfiguration(self):
             self.cP.read(localpath)
             for i in range(pdfguiglobals.MAXMRU, 0, -1):
                 if self.cP.has_option("MRU", str(i)):
-                    filename = self.cP.getquoted("MRU", str(i))
+                    filename = self.cP.get("MRU", str(i))
                     if filename:
                         self.fileHistory.AddFileToHistory(filename)
 
@@ -1029,7 +1029,7 @@ def updateConfiguration(self):
 
         for i in range(self.fileHistory.GetCount()):
             item = self.fileHistory.GetHistoryFile(i)
-            self.cP.setquoted("MRU", str(i + 1), item)
+            self.cP.set("MRU", str(i + 1), item)
 
         # Window size
         if not self.cP.has_section("SIZE"):
@@ -2522,8 +2522,7 @@ def onSaveCalc(self, event):
     def onDocumentation(self, event):
         """Show information about the documentation."""
         import webbrowser
-
-        from six.moves.urllib.request import pathname2url
+        from urllib.request import pathname2url
 
         url = "file://" + pathname2url(docMainFile)
         webbrowser.open(url)
diff --git a/src/diffpy/pdfgui/utils.py b/src/diffpy/pdfgui/utils.py
index 4a052a8e..e53a4c68 100644
--- a/src/diffpy/pdfgui/utils.py
+++ b/src/diffpy/pdfgui/utils.py
@@ -19,14 +19,6 @@
 """
 
 
-import six
-import six.moves.cPickle as pickle
-from six.moves.configparser import RawConfigParser
-
-# protocol=2 keep project files compatible with Python 2
-# PDFGUI_PICKLE_PROTOCOL = 2
-
-
 def numericStringSort(lst):
     """Sort list of strings inplace according to general numeric value.
     Each string gets split to string and integer segments to create keys
@@ -47,18 +39,6 @@ def numericStringSort(lst):
     return
 
 
-def pickle_loads(sdata, encoding="latin1"):
-    """Mimic interface of Python 3 pickle.loads.
-
-    Using encoding='latin1' is required for unpickling NumPy arrays and
-    instances of datetime, date and time pickled by Python 2.
-
-    Return the reconstructed object hierarchy.
-    """
-    rv = pickle.loads(sdata, encoding=encoding) if six.PY3 else pickle.loads(sdata)
-    return rv
-
-
 def safeCPickleDumps(obj):
     """Get pickle representation of an object possibly containing NaN or Inf.
     By default it uses pickle.HIGHEST_PROTOCOL, but falls back to ASCII
@@ -68,6 +48,9 @@ def safeCPickleDumps(obj):
 
     Return pickle string.
     """
+
+    import pickle
+
     ascii_protocol = 0
     try:
         s = pickle.dumps(obj, pickle.HIGHEST_PROTOCOL)
@@ -76,61 +59,10 @@ def safeCPickleDumps(obj):
     return s
 
 
-# This should be unnecessary in Python 3
-# TODO - replace getquoted/setquoted with get/set after dropping Python 2
-
-
-class QuotedConfigParser(RawConfigParser):
-    def getquoted(self, section, option):
-        """Retrieve option value previously set with setquoted.
-
-        This allows to work with unicode strings.
-        """
-        vq = self.get(section, option)
-        rv = vq.decode("utf-8") if six.PY2 else vq
-        return rv
-
-    def setquoted(self, section, option, value):
-        """Set option to a value encoded with urllib.quote.
-
-        This allows to store and write out unicode strings.
-        Use getquoted to recover the decoded value.
-        """
-        vq = value.encode("utf-8") if six.PY2 else value
-        return self.set(section, option, vq)
-
-
-# class QuotedConfigParser
-
-
-def quote_plain(s):
-    """Return a possibly Unicode string quoted as plain ASCII.
-
-    The returned value is suitable as a path component in the
-    project file format.
-    """
-    from six.moves.urllib.parse import quote_plus
-
-    rv = quote_plus(asunicode(s).encode("utf-8"))
-    return rv
-
-
-def unquote_plain(s):
-    """Unquote string previously encoded with quote_plain."""
-    from six.moves.urllib.parse import unquote_plus
-
-    u = unquote_plus(s)
-    rv = asunicode(u)
-    return rv
-
-
 def asunicode(s):
-    """Convert string or bytes object to a text type.
-
-    This is `unicode` in Python 2 and `str` in Python 3.
-    """
+    """Convert string or bytes object to a text type."""
     rv = s
-    if not isinstance(s, six.text_type):
+    if not isinstance(s, str):
         rv = s.decode("utf-8")
     return rv