Mn/Zr oxide catalysts having variation in Mn content were prepared by precipitation method, and their structure and catalytic properties were studied by means of nitrogen adsorption, XRD, ESCA and the CO hydro-gentation reaction. After calcinating the amorphous zirconium oxide, it crystallized into the monoclinic phase, resulting in increases in the crystallite size and the pore size. Introduction of manganese oxide into zirconium oxide retarded the crystallization of the amorphous zirconium oxide and increased the specific surface area of the catalyst. The surface of Mn/Zr oxide catalysts was appreciably enriched in manganese oxide and zirconium oxide exhibited high selectivities toward short chain olefins. Active site of Mn/Zr oxide catalysts was manganese oxide finely dispersed on the surface of zirconium oxide. However, the formation of solution in Mn/Zr oxide catalysts decreased selectivities of C₂-C₄ hy-drocarbons.