diff --git a/ChangeLog b/ChangeLog
index fbd1148..4ff0772 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,9 +1,10 @@
-2015-12-16  Juergen Knoedlseder  <jurgen.knodlseder@irap.omp.eu>
+2015-12-17  Juergen Knoedlseder  <jurgen.knodlseder@irap.omp.eu>
 
         * Version 1.0.0 released
         ========================
 
         Update end-user documentation
+        Change GException to RuntimeError in cscripts (#1604)
         Adapt to GammaLib interface changs (#1603)
         Implement handling of stacked data in csspec (#1566)
         Resolve Python test problem on El Capitan (#1563)
diff --git a/NEWS b/NEWS
index 9f18a39..05c5207 100644
--- a/NEWS
+++ b/NEWS
@@ -2,7 +2,7 @@ New Features and Important Changes in ctools 1.0.0
 
 Author(s) : Juergen Knoedlseder
 
-16 December 2015
+17 December 2015
 
 
 1. Introduction
@@ -111,6 +111,9 @@ requested energy binning, it selects for each spectral energy bin the
 relevant energy bins from the counts cube and performs a maximum likelihood
 analysis.
 
+All GExceptions are replaced by Python RuntimeErrors as the GException
+classes are not exposed to Python.
+
 
 20. Examples
 ------------
diff --git a/cscripts/csobsdef.py b/cscripts/csobsdef.py
index 0c54f02..0b4a4aa 100755
--- a/cscripts/csobsdef.py
+++ b/cscripts/csobsdef.py
@@ -249,8 +249,7 @@ class csobsdef(ctools.cscript):
                 pntdir = gammalib.GSkyDir()
                 pntdir.lb_deg(lon,lat)
             else:
-                raise gammalib.GException.invalid_value(self.name,
-                      "No (ra,dec) or (lon,lat) columns found in pointing"
+                raise RuntimeError("No (ra,dec) or (lon,lat) columns found in pointing"
                       " definition file.")
             obs.pointing(gammalib.GCTAPointing(pntdir))
 
diff --git a/cscripts/cssens.py b/cscripts/cssens.py
index 64f34a7..a0a12ae 100755
--- a/cscripts/cssens.py
+++ b/cscripts/cssens.py
@@ -241,7 +241,7 @@ class cssens(ctools.cscript):
             else:
                 msg = "Invalid sensitivity type \""+self.m_type+"\" encountered."+ \
                       " Either use \"Differential\" or \"Integral\"."
-                raise gammalib.GException.invalid_value("cssens", msg)
+                raise RuntimeError(msg)
 
             # Determine sensitivity
             result = self.get_sensitivity(self.obs, emin, emax,
@@ -347,7 +347,7 @@ class cssens(ctools.cscript):
         if not model.has_par("Prefactor"):
             msg = "Model \""+self.m_srcname+"\" has no parameter \"Prefactor\"."+ \
                   " Only spectral models with a \"Prefactor\" parameter are supported."
-            raise gammalib.GException.invalid_value("cssens", msg)
+            raise RuntimeError(msg)
 
         # Set source position
         if self.m_ra != None and self.m_dec != None:
diff --git a/cscripts/csspec.py b/cscripts/csspec.py
index 54a6349..bbe80a0 100755
--- a/cscripts/csspec.py
+++ b/cscripts/csspec.py
@@ -206,7 +206,7 @@ class csspec(ctools.cscript):
                       "cube does not overlap with specified energy range ["+ \
                       str(emin)+", "+str(emax)+"]. Specify "+ \
                       "overlapping energy range."
-                raise gammalib.GException.invalid_argument("csspec", msg)
+                raise RuntimeError(msg)
 
             # Determine number of layers to use for each spectral bin
             n_layers = int(len(use_layers) / self.m_enumbins)
diff --git a/cscripts/cstsdist.py b/cscripts/cstsdist.py
index 282d2c8..c4b2b49 100755
--- a/cscripts/cstsdist.py
+++ b/cscripts/cstsdist.py
@@ -275,7 +275,7 @@ class cstsdist(ctools.cscript):
         if not model.has_par("Prefactor"):
             msg = "Model \""+self.m_srcname+"\" has no parameter \"Prefactor\"."+ \
                   " Only spectral models with a \"Prefactor\" parameter are supported."
-            raise gammalib.GException.invalid_value("cssens", msg)
+            raise RuntimeError(msg)
 
         # Fit or fix spatial parameters
         if fitpos: