The influence of silver(I) catalyst on the oxidation of L-glutamine (Gln) by cerium(IV) in perchlorate solutions was studied spectrophotometrically. The study was carried out at a constant ionic strength of 1.0 mod dm-3 and a temperature of 25o C. In both uncatalyzed and Ag(I)-catalyzed paths, the reactions exhibited first order kinetics with respect to [Ce(IV)] and [Ag(I)], and less than unit order with respect to [Gln]. The reactions exhibited negative fractional-first order kinetics with respect to [H+]. Increasing both ionic strength and dielectric constant increased the oxidation rates. Addition of cerium(III) ion as a reaction product did not affect the rates. The rate of Ag(I)-catalyzed oxidation was found to be about seven times higher than that of uncatalyzed one. Ce(OH)3+ was suggested to be the kinetically active species of cerium(IV) under the experimental conditions. Probable mechanistic schemes for both uncatalysed and catalysed reactions are proposed. In both paths, the final oxidation products of L-glutamine are identified as formyl propanamide, ammonium ion, and carbon dioxide. The rate-law expressions consistent with the reactions mechanisms are derived. The activation parameters are evaluated and discussed.