Intense lasing of XeCl (180 mJ) and KrCl (100 mJ) occurs using HCl as the halogen doner. The low energies obtained from e‐beam devices are believed to result from Ar+2molecular‐ion absorption. Very long XeCl lasing lifetime with respect to gas fill is observed; this is postulated to be the result of photodissociation of Cl2due to the laser wavelength which, in turn, results in enhanced rates for the formation of HCl.