Spectroscopic examination of humic substances from river, lake and sea water as well as from river and lake sediments in the UV-VIS region indicated that the E₂₄₀/E₄₂₀ ratios of water humic substances differ significantly from those of sediment humic substances. A cluster analysis based on the absorption spectra of the humic substances revealed a similar fact. Con-sidering the hutnic substances from fresh water and sea water respectively, linear relationship between the optical density and the total organic carbon content of the samples implied that a spectrophotometric method (e.g. at 220 nrn) for determination of humic substances concentra-tion is possible.