When pure liquid methanol is radiolyzed by Co60 gamma-rays at room temperature, the yields of measured products are G(H2) = 5.39; G(CH4) = 0.54; G(CO)[image] 0.12;,G(HCHO) = 1.84; G(glycol) = 3.63. In the presence of iodine, all yields, except of CO, are decreased. The value of G(H2) is a gradual function of I2 concentration, but the effect on G(CH4) is an abrupt drop to an estimated value [image] 0.19 at [I2] < 3 x 10-3[image]. The results are interpreted in terms of 3 primary excitation processes: to an ionized state, to a triplet state, and to a singlet state. Important roles are played by free-radical decomposition processes, by ultimate-molecule rearrangement processes, and by metathetical reactions involving either normal CH3OH and ionized CH3OH+ plus an associated electron or two excited CH3OH molecules. The depressant effect of I2 on yield may be ascribed both to scavenging of free radicals and to capture of free electrons with resultant interference with ion-neutralization processes. Stern-Volmer reactions of I2 and excited molecules are not necessary to interpret the results. Some preliminary results of the effects of halides on yields from radiolysis of methanol are described.