The cobaltnitrosoalkylresorcinolate method enables a selective determination of the total content of resorcinol series phenols Sigma C-R in waste water of oil shale processing enterprises containing both mono- and dihydric phenols. The absorbance of phenol-containing solutions is measured at two combinations of NaNO2 concentration and wavelength - E(I) and E(II). Sigma C-R = = pE(I) - qE(11). Five combinations of standard compounds used for the determination of coefficients p and q are evaluated. Analytical instruction is presented.