A new selective colorimetric method for determination of resorcinol and its alkyl derivatives (1,3-benzenediols), the main phenolic pollutants in Estonia, has been elaborated. The overall reactions of the formation of cobalt-nitroso(alkyl)-resorcinolates according to this method are presented. The results of the experiments to find optimum values for pH and reagent concentrations as well as spectra of complexes formed from mono- and dialkyl derivatives of resocinol are presented. Analytical instruction and parameters of calibration curves for main phenolic components in retort water of Baltic ＇＇kukersite＇＇ oil shale ave given.