The effect of group IIIA-VIA elements and oxides on graphite oxidation was determined. Additives were moulded with spectroscopically pure graphite powder. The concentration was maintained constant at 0.1 mole per cent based on the element. The rate of reaction with 1 atm of air was measured at 700 and 800°C. Air flow rate from 2000 to 3000 cm3/min had no effect on the oxidation rate of the pure graphite at 700, 750 and 8OO"C, indicating that reaction was not occurring in zone III. The calculated En of 54 kcal/mole suggested reaction in zone 1. Visual inspection of the rods after reaction substantiated this conclusion. The reaction was first order with respect to oxygen partial pressure at 700 and 800°C. B, B,06, P and P,O, inhibited the oxidation of graphite at 700 and SOO"C, while the other elements and oxides catalysed the reaction to various degrees. The reaction remained kinetically of the first order when inhibited. A systematic variation in reaction rates appears to follow the diagonals of the periodic relationship of the element from the upper left to the lower right. These variations can be correlated with average ionization energy or electron affinity. Very tine powder Very fine powder *A. D. Mackay, Inc. *Anderson Chemical Co. fMatheson, Coleman and Bell $J. T. Baker Chemical Co. IlFisher Scientific Co. Q Harshaw Scientific Co.