The rate constants for quenching of theBstates of HgBr and HgI by the rare gases and simple halogenated molecules have been measured. The experimental approach consisted of photodissociating either HgBr2or HgI2(in the presence of the desired quenching gas) and recording the subsequent radiative decay of the HgX(X=Br or I) excited‐state population. The large rate constant determined for two‐body destruction of HgBr (B) by Hg (1.3×10−10cm3 sec−1) and bromine donors (Br2 : 5.5×10−10cm3 sec−1) enhances the attractiveness of HgBr lasers pumped by dissociative excitation of HgBr2.