diff --git a/gui/wxpython/gmodeler/model.py b/gui/wxpython/gmodeler/model.py
index 0c2d62e006c..9d0f58ec7d4 100644
--- a/gui/wxpython/gmodeler/model.py
+++ b/gui/wxpython/gmodeler/model.py
@@ -3333,6 +3333,12 @@ def __init__(self, fd, model, grassAPI="script"):
         self._writePython()
 
     def _getStandardizedOption(self, string):
+        """Return GRASS standardized option based on specified string.
+
+        :param string: input string to be converted
+
+        :return: GRASS standardized option as a string or None if not converted
+        """
         if string == "raster":
             return "G_OPT_R_MAP"
         elif string == "vector":
@@ -3346,7 +3352,7 @@ def _getStandardizedOption(self, string):
         elif string == "region":
             return "G_OPT_M_REGION"
 
-        return ""
+        return None
 
     def _writePython(self):
         """Write model to file"""
@@ -3390,7 +3396,8 @@ def _writePython(self):
 
         modelItems = self.model.GetItems(ModelAction)
         for item in modelItems:
-            for flag in item.GetParameterizedParams()["flags"]:
+            parametrizedParams = item.GetParameterizedParams()
+            for flag in parametrizedParams["flags"]:
                 if flag["label"]:
                     desc = flag["label"]
                 else:
@@ -3414,7 +3421,7 @@ def _writePython(self):
                     self.fd.write("# % answer: False\n")
                 self.fd.write("# %end\n")
 
-            for param in item.GetParameterizedParams()["params"]:
+            for param in parametrizedParams["params"]:
                 if param["label"]:
                     desc = param["label"]
                 else:
@@ -3441,6 +3448,29 @@ def _writePython(self):
                     self.fd.write("# % answer: {}\n".format(param["value"]))
                 self.fd.write("# %end\n")
 
+        # variables
+        for vname, vdesc in self.model.GetVariables().items():
+            self.fd.write("# %option")
+            optionType = self._getStandardizedOption(vdesc["type"])
+            if optionType:
+                self.fd.write(" {}".format(optionType))
+            self.fd.write("\n")
+            self.fd.write(
+                r"""# % key: {param_name}
+# % description: {description}
+# % required: yes
+""".format(
+                    param_name=vname,
+                    description=vdesc.get("description", ""),
+                )
+            )
+            if optionType is None and vdesc["type"]:
+                self.fd.write("# % type: {}\n".format(vdesc["type"]))
+
+            if vdesc["value"]:
+                self.fd.write("# % answer: {}\n".format(vdesc["value"]))
+            self.fd.write("# %end\n")
+
         # import modules
         self.fd.write(
             r"""
@@ -3489,8 +3519,11 @@ def cleanup():
             self.fd.write("    pass\n")
 
         self.fd.write("\ndef main(options, flags):\n")
+        modelVars = self.model.GetVariables()
         for item in self.model.GetItems(ModelAction):
-            self._writeItem(item, variables=item.GetParameterizedParams())
+            modelParams = item.GetParameterizedParams()
+            modelParams["vars"] = modelVars
+            self._writeItem(item, variables=modelParams)
 
         self.fd.write("    return 0\n")
 
@@ -3533,6 +3566,45 @@ def _writePythonAction(self, item, variables={}, intermediates=None):
             strcmd + self._getPythonActionCmd(item, task, len(strcmd), variables) + "\n"
         )
 
+    def _substitutePythonParamValue(
+        self, value, name, parameterizedParams, variables, item
+    ):
+        """Substitute parameterized options or variables.
+
+        :param value: parameter value to be substituted
+        :param name: parameter name
+        :param parameterizedParams: list of parameterized options
+        :param variables: list of user-defined variables
+        :param item: item object
+
+        :return: substituted value
+        """
+        foundVar = False
+        parameterizedValue = value
+
+        if name in parameterizedParams:
+            foundVar = True
+            parameterizedValue = 'options["{}"]'.format(self._getParamName(name, item))
+        else:
+            # check for variables
+            formattedVar = False
+            for var in variables["vars"]:
+                pattern = re.compile("%" + var)
+                found = pattern.search(value)
+                if found:
+                    foundVar = True
+                    if found.end() != len(value):
+                        formattedVar = True
+                        parameterizedValue = pattern.sub(
+                            "{options['" + var + "']}", value
+                        )
+                    else:
+                        parameterizedValue = f'options["{var}"]'
+            if formattedVar:
+                parameterizedValue = 'f"' + parameterizedValue + '"'
+
+        return foundVar, parameterizedValue
+
     def _getPythonActionCmd(self, item, task, cmdIndent, variables={}):
         opts = task.get_options()
 
@@ -3560,11 +3632,18 @@ def _getPythonActionCmd(self, item, task, cmdIndent, variables={}):
                     value = list(map(float, value))
 
             if (name and value) or (name in parameterizedParams):
-                foundVar = False
-
-                if name in parameterizedParams:
-                    foundVar = True
-                    value = 'options["{}"]'.format(self._getParamName(name, item))
+                if isinstance(value, list):
+                    foundVar = False
+                    for idx in range(len(value)):
+                        foundVar_, value[idx] = self._substitutePythonParamValue(
+                            value[idx], name, parameterizedParams, variables, item
+                        )
+                        if foundVar_ is True:
+                            foundVar = True
+                else:
+                    foundVar, value = self._substitutePythonParamValue(
+                        value, name, parameterizedParams, variables, item
+                    )
 
                 if (
                     foundVar
@@ -3577,7 +3656,7 @@ def _getPythonActionCmd(self, item, task, cmdIndent, variables={}):
 
         ret += '"%s"' % task.get_name()
         if flags:
-            ret += ",\n{indent}flags='{fl}'".format(indent=" " * cmdIndent, fl=flags)
+            ret += ',\n{indent}flags="{fl}"'.format(indent=" " * cmdIndent, fl=flags)
             if itemParameterizedFlags:
                 ret += " + getParameterizedFlags(options, [{}])".format(
                     itemParameterizedFlags
@@ -3597,40 +3676,6 @@ def _getPythonActionCmd(self, item, task, cmdIndent, variables={}):
 
         return ret
 
-    def _substituteVariable(self, string, variable, data):
-        """Substitute variable in the string
-
-        :param string: string to be modified
-        :param variable: variable to be substituted
-        :param data: data related to the variable
-
-        :return: modified string
-        """
-        result = ""
-        ss = re.split(r"\w*(%" + variable + ")w*", string)
-
-        if not ss[0] and not ss[-1]:
-            if data:
-                return "options['%s']" % variable
-            else:
-                return variable
-
-        for s in ss:
-            if not s or s == '"':
-                continue
-
-            if s == "%" + variable:
-                if data:
-                    result += "+options['%s']+" % variable
-                else:
-                    result += "+%s+" % variable
-            else:
-                result += '"' + s
-                if not s.endswith("]"):  # options
-                    result += '"'
-
-        return result.strip("+")
-
 
 class ModelParamDialog(wx.Dialog):
     def __init__(