The catalytic hydrodechlorination of chlorobenzene with Ni/C, Pd/C and Ni98Pd2/C in ethanol was studied with D-2 and C-13{H-1} NMR. Two dechlorination routes of this reaction (ionic and free-radical) are suggested depending upon the nature of the active hydrogen species. At the same time two competitive sources of hydrogen for hydrogenolysis of the C-Cl bond - molecular hydrogen and solvent (ethanol) molecules -are readily apparent from experiments with molecular deuterium.