The vapor phase catalytic oxidation of 1-butene to maleic anhydride was studied over V-P/TiO₂ cata-lysts which different calcination temperatures. The evaluation of phase strongly depended on calcination temperature. The temperature of a structral transforma-tion of metal oxide from amorphous to crystalline was observed at 400℃ and that of titania from anatase to rutile was at 600℃. The structural changes had pronounced effect on the catalytic activity for the oxidation of 1-butene, and the max-imum yield of maleic anhydride was observed for the catalyst calcined at 520℃. The kinetics data were studied with a redox mechanism. The data obtained under the conditions of low partial pressure of butene could be explained in terms of the pseudo-first order kinetics.