The radiolysis of aqueous solutions of chloromethanes (dichloromethane, CH2Cl2; chloroform, CHCl3; and carbon tetrachloride, CCl4) was performed with γ-rays to doses sufficient to completely decompose the solute in order to estimate the effects of radiation on the long-term storage of mixed waste in enclosed containers. One of the main relevant products was the inorganic chloride anion, which increased in concentration with increasing radiation dose due to the reactions of radiolytic decomposition products of water with the chloromethane. The pH of the solutions was observed to decrease with irradiation due to the formation of H3O+ as the counter ion to Cl-, i.e. the main radiolytic decomposition product is hydrochloric acid. Polymer formation was observed in aerated solutions as a precipitate while deaerated solutions exhibited a slight turbidity. © 2006 Elsevier B.V. All rights reserved.