The kinetics of the permanganate oxidation of formic acid in aqueous perchloric acid a t 30°C were examined by the spectrophotometric method. The chemical reaction 2Mn0, A BHCOOH + 2H + -2Mn02 + 3C0, + 4H20. appears to proceed via several parallel reactions. The overall rate equation has been obtained by using statistical multilinear regression analysis of the 660 cases studied, and the presence in the rate equation of two new terms in relation to previous studies shows that both permanganate autocatalgtic effects and acid media inhibition must be taken into account when the reaction proceeds at constant ionic strength.