Configurational isomerization over platinized coal at 570 K and a hydrogen pressure of 100 Pa has produced an equilibrium mixture of seven perhydrofluoranthene (tetracyclo[10.3.1.0(2,7) 0(8,16)]hexadecane) epimers. By studying stereomodels and comparing them with the composition of an equilibrium mixture of epimeric perhydroacenaphthenes (the main structural fragment of perhydrofluoranthene), it is suggested that the epimeric perhydrofluoranthenes have a three-dimensional structure. The composition of the equilibrium mixture has been studied by gas chromatography and chromato-mass spectrometry. The mass spectra and chromatographic retention indices of the individual epimers are given.