The Szilard-Chalmers reaction has been observed in a number of crystalline compounds of tri- and hexavalent chromium. The effect of neutron and external gamma irradiation has also been investigated. It was found that in a series of alkali chromates and dichromates the retention varied from 50 to 90 percent, while ammonium chromate and dichromate were much lower. The results are interpreted in terms of hotatom reactions of the recoil fragments in the crystal, and hydrolysis and reduction reactions taking place on dissolution of the crystals.