Using a pulsed-micro catalytic reactor benzene and toluene were hydrogenated to cyclohexane and methylcyclohexane, respectively, in a temperature range 50-250 degrees C. Modified catalysts containing 0.35% Pt-Al2O3 were investigated. Modification was carried out via (a) introducing a second metal (Ir, Rh, Re and U) and (b) fluorination and chlorination with different halogen contents of 1,3 and 6 wt%. The study revealed that (1) all catalysts show good catalytic activities in the temperature range 125-150 degrees C, except Rh catalyst which is very active even at room temperature, (2) introducing either Ir or Re enhances Pt activity, while U inhibits this activity, (3) halogenation promotes the catalyst activity and (4) alkyl-substitution enhanced aromatic ring hydrogenation.