The kinetics of oxidation of diphenyl sulphoxide (DPSO) by bispyridinesilver (I) dichromate (BPSDC) has been studied in 50% (v/v) aqueous acetic acid medium at 308K. The reaction is first order with respect to [oxidant] and fractional order dependence with respect to [DPSO]. This reaction is catalysed by [H+] and oxalic acid. Decrease the dielectric constant of the medium increases the rate. The reaction has been conducted at four different temperature and the activation parameters were calculated. From the observed kinetic results a suitable mechanism was proposed and substantiated with the rate law.