Abstract Gamma radiation induced removals of four halomethanes, with low initial concentrations in drinking water were investigated. The results show that absorbed dose and solution pH are important factors in affecting halomethanes removals. High-absorbed dose and solution pH drive halomethanes removals. The reactions of halomethanes with e aq − play a crucial role in their removal processes. Halomethanes removal during the radiation follow a pseudo-first-order kinetics model. Gamma radiation results in a slight decrease in pH and TOC values of drinking water.