Experimental results obtained indicate that organofluorine and organochlorine compounds containing hydrogen atoms experience destructive photosorption on MgO aged for a long time in air under conditions close to the tropospheric ones. The photosorption rate is higher for halogen-containing hydrocarbons (HCH) including fluorine while being several times lower for chlorine-containing hydrocarbons. The amount of photosorbed HCH at room temperature and at the pressure of 1 Pа can exceed 15% of MgO surface, that confirms the hypothesis of a substantial contribution of the photoprocesses on the MgO surface to removal of these HCH from the troposphere. The absence of photosorption activity with respect to HCH on gamma-Al2O3 (Ssp = 150 m2/g) and SiO2 (Ssp = 500 m2/g) is connected with the difference in crystallinity of the studied oxide powders.