KX-ray-gated emission Mössbauer spectra of57Co-labelled CoF2 and CoF2.2H2O were measured at room temperature, using the coincidence technique. A difference was found in the relative intensity of57Fe(II)/57Fe(III) between the X-ray-gated and non-gated emission spectra. The results are explained in terms of local radiolytic effects of water of crystallization and the chemical effects associated with the de-excitation processes caused by EC-decay.