As a biodiesel by-product, glycerol is a potential re-newable building block for sustainable chemistry.[1] It is a C3 platform molecule, potentially leading to several interesting iso-carbon chemicals such as propanediols, lactic acid, acrylic acid, etc. It can also be seen a prototypical polyalcohol: results achieved with this substrate could be extended to higher polyols such as glucose, starch, etc. The hydrogenolysis reaction catalyzed by a transition metal solid catalyst in basic conditions is a potential way to transform glycerol into important chemicals.[2] Several parameters could play a role in the control of the reaction selectivity: nature of the metal catalyst, pH of the solution, nature of the atmosphere, temperature and pressure, etc. Those parameters have been probed experimentally. In particular, we will compare activities and selectivities achieved in the presence of rhodium or iridium catalyst under inert or reductive atmosphere. Moreover, to govern the catalyst design towards highly selective processes, a better insight into the reaction mechanism is still lacking. The two main hypothesis on the first step is either a dehydrogenation step, either a dehydration step. In agreement with experimental results, theoretical studies at the DFT level sustain the first step beeing a dehydrogenation step. We will detail the mechanism on Rh(111) and discuss the role of the metal catalyst. [1] A. Behr, J. Eilting, K. Irawadi, J. Leschinski, F. Lindner, Improved utilisation of renewable resources: New important derivatives of glycerol, Green Chemistry, 2008, 10, 13-30 [2] J. Chaminand, L. Djakovitch, P. Gallezot, P. Marion, C. Pinel and C. Rosier, Glycerol hydrogenolysis on heterogeneous catalysts, Green Chemistry, 2004, 6, 359-361.