This work concerns the influence of the hydrogen sulfide partial pressure and the sulfidation temperature on the hydrodeoxygenation activity and selectivity of a CoMo catalyst supported on activated carbon. An attempt is made to identify the active sites involved in the reaction of different oxygenated molecules: guaiacol demethylation and dehydroxylation, ethyldecanoate hydrogenation and decarboxylation, 4-methylacetophenone hydrogenation.