Manganese(III) acetate was prepared by the oxidation of manganese(II) acetate in aqueous acetic acid by electrolytic method. The anodically generated Mn(III) species was characterised by spectroscopic and redox potential studies. Conditions for the study of kinetics of Oxidation ofα-amino acids by Mn(III) in aqueous acetic acid was investigated. Plots of log[Mn(III)] versus time for the first order process, or Mn(III) versus time for zero order process were nonlinear. The rate constants computed from [Mn(III)](1/2) versus time plots were independent of [Mn(III)]0 indicating that the reaction goes through competitive zero and first order path-ways in [Mn(III)]0. The kinetic order in [amino acid], [H(+)] and [Mn(II)] were found out. Effect of added anions like CH3COO(-), F(-), Cl(-) and ClO 4 (-) were investigated. Evidence for the transient existence of the free radical reaction intermediate is given. Dependence of reaction rate on temperature is explained and activation parameters computed from Arrhenius and Eyring plots. A mechanism consistent with the observed results is proposed and discussed.