Glycerol steam reforming on Rh and Ni supported catalyst was investigate in view to produce syn-gas to feed a high temperature fuel cell system (SOFC-MCFC). Results obtained revealed that glycerol is subjected to pyrolysis phenomena and at temperature higher than 720 K drastically decomposes before to reach the catalyst surface. Rh/Al2O3 catalyst resulted to be more active and stable than Ni supported catalysts but independently from the catalyst used (Rh or Ni) and temperature investigated, the reaction is affected by coke formation mainly promoted by the large presence of olefins formed by glycerol thermal decomposition. Even if for thermodynamic reasons the hydrogen production should be favored by operating at high temperature, results obtained demonstrate that it is more convenient to operate at temperature not higher than 923 K, since higher reaction temperature promotes the formation of encapsulated carbon which negatively reflects on catalyst stability. (C) 2010 Elsevier B.V. All rights reserved.