The kinetics of oxidation of dl-mandelic acid (MA) by tripropylammonium fluorochromate (TriPAFC) was studied in aqueous acetic acid medium. The rate of reaction is first order with respect to TriPAFC, MA and [H+] and the reaction is catalyzed by hydrogen ion. The reaction was studied in the presence of oxalic acid (OA). The oxidation leads to the formation of the phenyl glyoxalic acid. Various thermodynamic parameters have been determined at different acetic acid-water composition. A suitable mechanism has been proposed.