diff --git a/doc/src/module.rst b/doc/src/module.rst
index a22db77..366148d 100644
--- a/doc/src/module.rst
+++ b/doc/src/module.rst
@@ -176,8 +176,8 @@ Module Interface
         This method is an extension to the DB API definition.
 
 
-.. function:: SessionPool(user, password, dsn, min, max, increment, \
-        connectiontype=cx_Oracle.Connection, threaded=False, \
+.. function:: SessionPool(user=None, password=None, dsn=None, min=1, max=2, \
+        increment=1, connectiontype=cx_Oracle.Connection, threaded=False, \
         getmode=cx_Oracle.SPOOL_ATTRVAL_NOWAIT, events=False, \
         homogeneous=True, externalauth=False, encoding=None, nencoding=None, \
         edition=None)
diff --git a/src/cxoBuffer.c b/src/cxoBuffer.c
index 2cf5418..28b9d39 100644
--- a/src/cxoBuffer.c
+++ b/src/cxoBuffer.c
@@ -23,7 +23,7 @@
 int cxoBuffer_fromObject(cxoBuffer *buf, PyObject *obj, const char *encoding)
 {
     cxoBuffer_init(buf);
-    if (!obj)
+    if (!obj || obj == Py_None)
         return 0;
     if (PyUnicode_Check(obj)) {
         buf->obj = PyUnicode_AsEncodedString(obj, encoding, NULL);
diff --git a/src/cxoSessionPool.c b/src/cxoSessionPool.c
index 33f06fc..1d7c3a3 100644
--- a/src/cxoSessionPool.c
+++ b/src/cxoSessionPool.c
@@ -169,9 +169,13 @@ static int cxoSessionPool_init(cxoSessionPool *pool, PyObject *args,
             NULL };
 
     // parse arguments and keywords
-    externalAuthObj = editionObj = NULL;
+    usernameObj = passwordObj = dsnObj = editionObj = Py_None;
+    externalAuthObj = NULL;
     threadedObj = eventsObj = homogeneousObj = passwordObj = NULL;
     connectionType = &cxoPyTypeConnection;
+    minSessions = 1;
+    maxSessions = 2;
+    sessionIncrement = 1;
     if (cxoUtils_initializeDPI() < 0)
         return -1;
     if (dpiContext_initCommonCreateParams(cxoDpiContext, &dpiCommonParams) < 0)
@@ -181,11 +185,11 @@ static int cxoSessionPool_init(cxoSessionPool *pool, PyObject *args,
             (uint32_t) strlen(dpiCommonParams.driverName);
     if (dpiContext_initPoolCreateParams(cxoDpiContext, &dpiCreateParams) < 0)
         return cxoError_raiseAndReturnInt();
-    if (!PyArg_ParseTupleAndKeywords(args, keywordArgs, "OOOiii|OObOOOssO",
-            keywordList, &usernameObj, &passwordObj, &dsnObj,
-            &minSessions, &maxSessions, &sessionIncrement, &connectionType,
-            &threadedObj, &dpiCreateParams.getMode, &eventsObj,
-            &homogeneousObj, &externalAuthObj, &dpiCommonParams.encoding,
+    if (!PyArg_ParseTupleAndKeywords(args, keywordArgs, "|OOOiiiOObOOOssO",
+            keywordList, &usernameObj, &passwordObj, &dsnObj, &minSessions,
+            &maxSessions, &sessionIncrement, &connectionType, &threadedObj,
+            &dpiCreateParams.getMode, &eventsObj, &homogeneousObj,
+            &externalAuthObj, &dpiCommonParams.encoding,
             &dpiCommonParams.nencoding, &editionObj))
         return -1;
     if (!PyType_Check(connectionType)) {
@@ -228,18 +232,14 @@ static int cxoSessionPool_init(cxoSessionPool *pool, PyObject *args,
 
     // populate parameters
     encoding = cxoUtils_getAdjustedEncoding(dpiCommonParams.encoding);
-    if (cxoBuffer_fromObject(&userNameBuffer, pool->username, encoding) < 0)
-        return -1;
-    if (cxoBuffer_fromObject(&passwordBuffer, passwordObj, encoding) < 0) {
-        cxoBuffer_clear(&userNameBuffer);
-        return -1;
-    }
-    if (cxoBuffer_fromObject(&dsnBuffer, pool->dsn, encoding) < 0) {
-        cxoBuffer_clear(&userNameBuffer);
-        cxoBuffer_clear(&passwordBuffer);
-        return -1;
-    }
-    if (cxoBuffer_fromObject(&editionBuffer, editionObj, encoding) < 0) {
+    cxoBuffer_init(&userNameBuffer);
+    cxoBuffer_init(&passwordBuffer);
+    cxoBuffer_init(&dsnBuffer);
+    cxoBuffer_init(&editionBuffer);
+    if (cxoBuffer_fromObject(&userNameBuffer, usernameObj, encoding) < 0 ||
+            cxoBuffer_fromObject(&passwordBuffer, passwordObj, encoding) < 0 ||
+            cxoBuffer_fromObject(&dsnBuffer, dsnObj, encoding) < 0 ||
+            cxoBuffer_fromObject(&editionBuffer, editionObj, encoding) < 0) {
         cxoBuffer_clear(&userNameBuffer);
         cxoBuffer_clear(&passwordBuffer);
         cxoBuffer_clear(&dsnBuffer);