Acidic compounds in cracked components of gasoline, isolated by extraction with aqueous solutions of sodium bicarbonate and sodium hydroxide, were identified as phenol and its mono-, di-, tri- and tetramethyl- derivatives. Aromatic sulfur compounds separated as the hexane and benzene fractions by chromatography on an alumina column were identified as thiophene, its mono-, di- and trimethyl- derivatives, ethylthiophene, benzothiophene and methylbenzothiophene. The identification of the phenolic compounds was achieved by IR, hydrogen-1 and carbon-13 NMR spectroscopy and GC - MS. Additionally, for complete identification of sulfur compounds a GC equipped with a selective sulfur detector was used. ISD Induction System Deposit (ISD) tests showed a decreased deposit-forming tendency for phenol compounds and no significant deposit formation for aromatic sulfur compounds or other fractions isolated.