AbstractSurface active substances as organic constituents of bulk precipitation were studied by AC voltammetric method. Adsorption characteristics at the mercury electrode of real rainwater samples are compared with aqueous solutions of a number model substances suggested to be representative of water soluble organic compounds (WSOC) in atmospheric aerosols and droplets: monocarboxylic, dicarboxylic, and polyacidic compounds, levoglucosan, polyaromatic hydrocarbon naphtalene and anionic surfactant sodium dodecylbenzene sulfonate. On the basis of the capacitance vs. potential curves and the surfactant activity normalized to the organic carbon content it is concluded that humic like substances, monocarboxylic acids and polyaromatic hydrocarbons may play an important role in atmospheric aquatic system because of their surface active potential.