The synthetic method of pyrazole was performed by 1,3-dipolar cycloaddition with dipolarophileinstead of the reaction between diazomethane and acetylene. The cycloaddition mechanism and reac-tivity of 3-phenyloxadiazole derivatives with dipolarophiles was investigated. In order to investigatethe mechanism and reactivity of this cycloaddition, the effect of substituents having various kinds ofelectron withdrawing of releasing groups were examinated. Considering the effect of substituents, anelectron withdrawing group attached at the 4-carbon position in 3-phenyloxadiazole derivatives decrease the reaction rate because of the lack of electron density on oxadiazole ring. The reaction rate of3-phenyloxadiazole derivatives with dipolarophiles were more conveniently measured using UV thanusing a volumetric analysis which was used before. From the result of this study, it was that thecycloaddition was found to be a first-order reaction depending upon the concentration of 3-phenyloxadiazole only.