The sol immobilization technique is widely employed for the synthesis of size- and morphology controlled supported nanoparticles. The protective agent adsorbed on the surface of nanoparticles can substantially affect the catalytic performances, by limiting the access to the active sites as well as by influencing metal-support and reactant-metal interactions, thus altering not only the activity but also the selectivity of the reaction. Herein, we studied the effect of the capping agent (specifically polyvinyl alcohol, PVA) removal on the catalytic activity and selectivity of gold nanoparticles supported on different carbon based materials using the glycerol oxidation as test reaction. (C) 2016 Elsevier B.V. All rights reserved.