diff --git a/pytriqs/wrap_test/g.hpp b/pytriqs/wrap_test/g.hpp
index 429ea49e..d0b8e12f 100644
--- a/pytriqs/wrap_test/g.hpp
+++ b/pytriqs/wrap_test/g.hpp
@@ -24,3 +24,23 @@ void pass_bgf(block_gf_view<imfreq> g) {
   h5_write(file, "g", g);
  }
 }
+
+// scalar gf
+
+gf_view<imfreq,scalar_valued> make_sgf(double a) {
+ double beta = 1;
+ auto G1 = gf<imfreq, scalar_valued>({beta, Fermion});
+{
+  H5::H5File file("ess_test_g3a.h5", H5F_ACC_TRUNC);
+  h5_write(file, "g", G1);
+ }
+ return G1;
+}
+
+void pass_sgf(gf_view<imfreq,scalar_valued> g) {
+
+ {
+  H5::H5File file("ess_test_g3b.h5", H5F_ACC_TRUNC);
+  h5_write(file, "g", g);
+ }
+}
diff --git a/pytriqs/wrap_test/test_g_desc.py b/pytriqs/wrap_test/test_g_desc.py
index a192c3fd..599d66b6 100644
--- a/pytriqs/wrap_test/test_g_desc.py
+++ b/pytriqs/wrap_test/test_g_desc.py
@@ -8,6 +8,10 @@ module.add_include("<pytriqs/converters/gf.hpp>")
 module.add_function (name = "make_bgf", signature = "block_gf_view<imfreq> (double a)", doc = "DOC of print_a")
 module.add_function (name = "pass_bgf", signature = "void (block_gf_view<imfreq> g) ", doc = "DOC of print_a")
 
+module.add_function (name = "make_sgf", signature = "gf_view<imfreq,scalar_valued> (double a)", doc = "DOC of print_a")
+module.add_function (name = "pass_sgf", signature = "void (gf_view<imfreq,scalar_valued> g)", doc = "DOC of print_a")
+
+
 if __name__ == '__main__' : 
    module.generate_code(mako_template = sys.argv[1], wrap_file = sys.argv[2])
    module.generate_py_converter_header(mako_template = sys.argv[3], wrap_file = sys.argv[4])
diff --git a/triqs/python_tools/wrapper_tools.hpp b/triqs/python_tools/wrapper_tools.hpp
index a422189d..4934b358 100644
--- a/triqs/python_tools/wrapper_tools.hpp
+++ b/triqs/python_tools/wrapper_tools.hpp
@@ -1,5 +1,4 @@
-
-    #pragma once
+#pragma once
 #include <Python.h>
 #include "structmember.h"
 #include <string>
@@ -27,7 +26,6 @@ namespace triqs { namespace py_tools {
 //--------------------- pyref -----------------------------
 
 // a little class to hold an owned ref, make sure it is decref at destruction
-// with some useful factories.
 class pyref {
  PyObject * ob = NULL;
  public:
@@ -46,9 +44,6 @@ class pyref {
  pyref(pyref && p){ ob = p.ob; p.ob=NULL;}
  pyref& operator =(pyref const&) = delete;
  pyref& operator =(pyref &&p) {ob = p.ob; p.ob=NULL; return *this;}
- // factories. No public constructor.
- // The point is that PyObject is borrowed or new, depending on the function that produced it
- // Need to check in the API doc for each case.
  static pyref module(std::string const &module_name) { return PyImport_ImportModule(module_name.c_str()); }
  static pyref string(std::string const &s) { return PyString_FromString(s.c_str());} 
 };
@@ -58,18 +53,19 @@ class pyref {
 //---------------------  py_converters -----------------------------
 
 // default version for a wrapped type. To be specialized later.
+// py2c behaviour is undefined is is_convertible return false
 template<typename T> struct py_converter;
- //static PyObject * c2py(T const & x);
- //static T & py2c(PyObject * ob);
- //static bool is_convertible(PyObject * ob, bool raise_exception);
- //
+ //{ 
+ //  static PyObject * c2py(T const & x);
+ //  static T & py2c(PyObject * ob);
+ //  static bool is_convertible(PyObject * ob, bool raise_exception);
+ //}
 
 // We only use these functions in the code, not converter
 // TODO : Does c2py return NULL in failure ? Or is it undefined...
 template <typename T> static PyObject *convert_to_python(T &&x) {
  return py_converter<typename std::decay<T>::type>::c2py(std::forward<T>(x));
 }
-// can convert_from_python raise a triqs exception ? NO
 template<typename T> static auto convert_from_python(PyObject * ob) -> decltype(py_converter<T>::py2c(ob)) { return py_converter<T>::py2c(ob);}
 template <typename T> static bool convertible_from_python(PyObject *ob, bool raise_exception) {
  return py_converter<T>::is_convertible(ob, raise_exception);
@@ -371,19 +367,6 @@ template <> struct py_converter<triqs::arrays::range> {
  }
 };
 
-// --- gf<U...> ----
-/*template <typename ...U > struct py_converter<triqs::gfs::gf<U...>> {
- using conv = py_converter<triqs::gfs::gf_view<U...>>;
- static PyObject *c2py(triqs::gfs::gf<U...> &g) { return conv::c2py(g); }
- static PyObject *c2py(triqs::gfs::gf<U...> &&g) { return conv::c2py(g); }
- static bool is_convertible(PyObject *ob, bool raise_exception) {
-  return conv::is_convertible(ob,raise_exception);
- }
- static triqs::gfs::gf<U...> py2c(PyObject *ob) { return conv::py2c(ob); }
-};
-*/
-
-
 // --- nothing  <--> None ----
 #ifdef TRIQS_GF_INCLUDED
 
@@ -409,9 +392,7 @@ template <typename... T> struct py_converter<triqs::gfs::gf_view<triqs::gfs::blo
  using gf_view_type = triqs::gfs::gf_view<T...>;
  using c_type = triqs::gfs::gf_view<triqs::gfs::block_index, gf_type>;
 
- static PyObject *c2py(c_type &&g) { return c2py(g);}
-
- static PyObject *c2py(c_type &g) {
+ static PyObject *c2py(c_type g) {
   // rm the view_proxy
   std::vector<gf_view_type> vg; 
   vg.reserve(g.data().size());
@@ -448,6 +429,29 @@ template <typename... T> struct py_converter<triqs::gfs::gf_view<triqs::gfs::blo
  }
 };
 
+// Converter for scalar_valued gf : reinterpreted as 1x1 matrix
+template <typename Variable, typename Opt> struct py_converter<triqs::gfs::gf_view<Variable, triqs::gfs::scalar_valued, Opt>>{
+
+ using conv = py_converter<triqs::gfs::gf_view<Variable, triqs::gfs::matrix_valued, Opt>>;
+ using c_t = triqs::gfs::gf_view<Variable, triqs::gfs::scalar_valued, Opt>;
+
+ static PyObject *c2py(c_t g) {
+  return conv::c2py(reinterpret_scalar_valued_gf_as_matrix_valued(g));
+ }
+
+ static bool is_convertible(PyObject *ob, bool raise_exception) {
+  if (!conv::is_convertible(ob,raise_exception)) return false;
+  auto g = conv::py2c(ob); // matrix view
+  if (get_target_shape(g) == make_shape(1,1)) return true;
+  if (raise_exception) PyErr_SetString(PyExc_RuntimeError,"The green function is not of dimension 1x1 : can not be reinterpreted as a scalar_valued Green function");
+  return false;
+ }
+
+ static c_t py2c(PyObject *ob) {
+  return slice_target_to_scalar(conv::py2c(ob),0,0);
+ }
+};
+
 #endif
 
 // ---- function ----