Abstract: Various kinds of metal oxides which were intentionally dispersed on glassy carbon electrode surfaces reveal catalytic activities for the oxidation of ascorbic acid and oxalic acid. The highest catalytic activities among many metal oxides dispersed on glassy carbon electodes were shown at ZrO₂,CeO₂, Co₂O₃,Cr₂O₃, SnO₂ and α-Al₂O₃. The electrocatalytic behaviours in relation with the properties of metal oxides and the mechanism of oxidation process wasinvestigated using chronoamperometry, chronopotentiometry and cyclic voltametry.