Kinetics of oxidation of some essential amino acids by N- chlorosaccharin (NCSA) in aqueous acetic acid medium have been investigated. The observed rate of oxidation is first order with respect to [amino acid], [NCSA] and [H⁺]. A small increase in rate is observed with increase in concentration of acetic acid. No significant effect was observed by the addition of sodium perchlorate and saccharin. The oxidation product was identified by the use of TLC. Mechanism consistent with observed results under different conditions have also been proposed. The rate -limiting steps have been identified and the corresponding constants have been computed at different temperatures. The activation parameters have been computed from the latter constants.