The kinetics of oxidation of mandelic acid by Imidazolium dichromate has been studied in 50% acetic acid – water (v/v) medium in the presence of perchloric acid at 303K. The reaction is the First order with Respect to [oxidant], and Fractional order with respect to [substrate] and [acid]. Hence, Michaelis menten types of kinetics has been observed. The decrease in dielectric constant of the medium increases the rate of the Reaction. Increase in ionic strength by the addition of sodium-perchlorate has no effect on the rate constant. There is no polymerization with acrylonitrile. The reaction has been studied at five different temperatures and the activation parameters were calculated. The oxidation of mandelic acid resulted in the formation of corresponding oxoacid has been identified as the product of oxidation. From the observed kinetic results a suitable mechanism with rate data has been proposed.