Kinetic investigation on the hexachloroplatinate(IV) (HCP) oxidation of L-histidine (His) catalyzed by zirconium(IV) has been performed in sulfuric acid medium at constant ionic strength and temperature. The reaction has been followed spectrophotometrically. A first order dependence on [HCP] and fractional-first order dependences with respect to [His], [acid] and [Zr(IV)] are obtained. Increasing ionic strength and dielectric constant decreases the oxidation rate. On the basis of the experimental results, a suitable mechanism has been proposed. The reaction is suggested to proceed via formation of zirconium(IV)-histidine intermediate complex, which reacts with the oxidant by an inner-sphere mechanism leading to decomposition of the complex in the rate-determining step to give rise to the oxidation products which are identified as the corresponding aldehyde (2-imidazole acetaldehyde), ammonium ion and carbon dioxide. The appropriate rate law is deduced and the activation parameters are evaluated and discussed.