The influence of the neutron dose, the neutron spectrum and the sample preparation on Argon diffusion in neutron-irradiated KCl crystals was investigated. No effect of the concentration of the rare gas atoms nore of any other aliovalent atoms produced by nuclear reactions was observed. However radiation damage introduced by the fission neutrons seemed to influence the diffusion behavior. This radiation-damage could be annealed in the presence of thermal or slow epithermal neutrons. Lattice defects which are developed by cleaving of the crystals influenced the gas diffusion too.