Concentrates of high-molecular weight petroleum phenols and their trimethylsilyl derivatives were isolated and studied by means of mass spectrometry and IR spectroscopy. Homologous series of multiatomic phenols were identified in the concentrates investigated: bis-hydroxy-phenylmethanes and other classes of phenol compound with uncondensed aromatic nuclei with the empirical formulae CnH2n-14O2, CnH2n-16O2 and CnH2n-22O3. The presence of these compounds in concentrates of petroleum phenols was previously unknown.