The hydrogenolysis of a series of alkylcesiums in cyclohexylamine solvent has been studied spectrophotometrically. The cesium salt of p-phenyltoluene reacts with H2 (1 atm, room temperature), but the cesium salts of di-2,4-xylylmethane and of diphenylmethane are unreactive. The results show that the acidity of H2 is intermediate between those of p-phenyltoluene and of di-2,4-xylylmethane in this reaction system. Possible effects of ion association phenomena on the equilibrium processes are considered.