Co3O4 catalyst was prepared by means of precipitation method and its precursor was treated with formic acid to prepare H-Co3O4 catalyst. Their catalytic activities for N2O catalytic decomposition were studied. The results show that H-Co3O4 catalyst exhibits much higher catalytic activity than Co3O4, which may result from the larger BET surface area, especially the more amount of surface Co3+, enhanced reducibility and promoted desorption ability of oxygen species.