The effect on moisture absorption of introducing bromine into epoxy resins is investigated. The research is carried out with a tetraglycidyl 4,4′‐diaminodiphenyl methane/4,4′‐diaminodiphenyl sulfone system, and compared with a reference system of diglycidyl ether of bisphenol A/diaminodiphenyl methane epoxy, both systems containing brominated reactive epoxy additives. The results indicate that the presence of bromine reduces drastically the rate and the maximum level of moisture absorption. The presence of bromine is shown to have only a small effect on the high‐temperature properties and on the glass‐transition temperatures of the dry resins. Moreover, due to their lower moisture absorption capacity, the glass‐transition temperatures of the wet brominated resins are higher than the counterparts of the original bromine‐free epoxies.