The photooxidation process using polychromatic UV xenon lamp and persulfate was studied for the destruction of cyanide in mining effluents, for example, potassium hexacyanoferrate. The kinetic regularities of a photooxidation process of hexacyanoferrates were studied (dependence on process parameters such as pH, temperature and concentration of the oxidant). The optimal molar ratio of oxidant to pollutant was found to be 20÷1. Comparative destruction hexacyanoferrate experiments showed that the efficiency of the destruction process in the selected oxidative systems can be changed in the following order: of {UV − VIS / PS} > {PS} > {UV − VIS}. High treatment efficiency of hexacyanoferrates using an oxidative system {UV − VIS} / PS is due to both in situ generation of ROS - hydroxyl and sulfate anion radicals and the disproportionation persulfate by Fe2+ / Fe3+ ions produced during the destruction of hexacyanoferrate complex.