diff --git a/TestON/bin/cli.py b/TestON/bin/cli.py
index a91052c..f29a8ec 100755
--- a/TestON/bin/cli.py
+++ b/TestON/bin/cli.py
@@ -267,6 +267,10 @@
                         index = index+1
                         options[option] = args[index]
                         options = self.testcasesInRange(index,option,args,options)
+                    elif re.match("--params", option, flags=0):
+                        # check if there is a params
+                        index = index + 1
+                        options['params'].append(args[index])
                 else :
                     options['testname'] = option
         except IndexError as e:
@@ -284,6 +288,8 @@
         options['testdir'] = None
         options['testcases'] = None
         options['onoscell'] = None
+        # init params as a empty list
+        options['params'] = []
         return options
 
     def testcasesInRange(self,index,option,args,options):
diff --git a/TestON/core/teston.py b/TestON/core/teston.py
index e798e98..a770490 100644
--- a/TestON/core/teston.py
+++ b/TestON/core/teston.py
@@ -781,7 +781,7 @@
     verifyTest( options )
     verifyExample( options )
     verifyTestScript( options )
-    verifyParams()
+    verifyParams( options )
     verifyLogdir( options )
     verifyMail( options )
     verifyTestCases( options )
@@ -929,7 +929,7 @@
     main.params = main.parser.parseParams( main.classPath )
     main.topology = main.parser.parseTopology( main.classPath )
 
-def verifyParams():
+def verifyParams( options ):
     try:
         main.params = main.params['PARAMS']
     except KeyError:
@@ -942,6 +942,40 @@
         print "Error with the Topology file: Either the file not specified " +\
               "or the format is not correct"
         main.exit()
+    # Overwrite existing params variables if they are specified from command line
+    if len(options.params) > 0:
+        # Some params variables are specified from command line
+        for param in options.params:
+            if not re.search( ".=.", param ):
+                print( "Error when parsing params: params should follow key=value format" )
+                continue
+            # Split the param string to netest keys and value
+            [ keys, value ] = param.split( "=" )
+            # Split the nested keys according to its hierarchy
+            keyList = keys.split( "/" )
+            # Get the outermost dictionary
+            paramDict = main.params
+            # Get the innermost dictionary
+            try:
+                while len( keyList ) > 1:
+                    key = keyList.pop(0)
+                    assert isinstance( paramDict[ key ], dict )
+                    paramDict = paramDict[ key ]
+            except KeyError:
+                print( "Error when parsing params: key \"" + key + "\" not found in main.params" )
+                main.exit()
+            except AssertionError:
+                print( "Error when parsing params: \"" + key + "\" is already the innermost level in main.params" )
+                main.exit()
+            # Change the value
+            if not paramDict.has_key( keyList[0] ):
+                print( "Error when parsing params: key \"" + keyList[0] + "\" not found in main.params" )
+                main.exit()
+            elif isinstance( paramDict[ keyList[0] ], dict ):
+                print( "Error when parsing params: more levels under key \"" + keyList[0] + "\" in main.params" )
+                main.exit()
+            else:
+                paramDict[ keyList[0] ] = value
 
 def load_parser():
     '''