Fulvic acids were extd. from Kolobrzeg mud with 0,2 M NaOH, sepd. on an ion-exchange resin and oxidized with NaOCl or H2O2 in aq. soln. at 200 degrees C for 24 h. In the reaction mixt., the presence of CH, Cl-2, CI(CH2)(3)Cl, C6H4Me2, AcOEt, PhH, PhMe, PhEt, AcOPr, C12H26, C10H22 and PhPr was evidenced by gas chromatog. The Cl-contg. compds. were detected when NaOCl was used as the oxidn. agent. The oxidn. with H2O2 resulted in formation of arom. hydrocarbons.