The kinetics and mechanism of the oxidation of lactic acid (LA) by pyridinium fluorochromate (PFC) has been studied by spectrophotometric method in 50% acetic acid – 50% water (v/v) medium in a temperature range of 298 K- 313 K. Under the conditions of the pseudo-first order, the reaction follows first order with respect to [LA], [H+] and [PFC]. The reaction is catalysed by perchloric acid. There is no salt effect. The rate increases with increase in the percentage of acetic acid and the plot of log kobs versus 1/D is linear with a positive slope indicating the positive ion – dipole nature of the reaction. Activation parameters have been evaluated. Based on the experimental results, a probable reaction mechanism of oxidation was proposed.