The gas-phase reactions of I+ and I2(+) with methane were studied to determine which species is involved in the oxidation of methane to methyl sulfate, an intermediate in the production of methanol. We found that while I+ reacts readily with methane, I2(+) does not react in our experimental reaction conditions. Reaction products and rate constants are measured and reported. In addition, ab initio calculations were carried out to further understand the reaction mechanism. A revised mechanism of catalysis is proposed which is in excellent agreement with available experimental data and our theoretical computations.