Abstract: Catalytic oxidation of methanol, ammonia and toluene with 2.0% Ru/Al₂O₃ and 2.0% Ru/AC (ACactive carbon) catalysts on a fixed-bed reactor in excess oxygen was studied. The activity test results showed that Ru/Al₂O₃ has a higher activity than Ru/AC. The threekinds of reactants showed the catalytic activity principle as methanol>ammonia>toluene. The conversion of the reactants rose with the increasing of concentration and then dropped with it. The active energy (Ea) of thereaction showed the order as methanol2O₃ was same as that of Ru/AC (0.54 mL/g); however, the pore diameters were very distinct from each other, whichwere9.3 nm and 2.3 nm for Ru/Al₂O₃ and Ru/AC respectively. Ru was highly dispersed on the alumina support with very small size (less than 3 nm); however, the Ru located on the surface of the active carbon was 4-10 nm. The main reason that Ru/Al₂O₃ was more active than Ru/AC may be caused by the smaller size and higher dispersion of Ru on the supports.