Bitumen and shale oils from selected Spanish oil shales that differ in geological age, depositional environment, and source location have been studied by solution H-1 nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Both bitumens and shale oils are dominated by aliphatic moieties as it is typically found in kerogens derived from algal/bacterial material. Several parameters calculated from the H-1 NMR and FTIR spectra provide useful information about the maturity of the oil shales in terms of relative aliphatic, aromatic, and carbonyl/carboxyl concentrations, aliphatic chain length, and type and degree of substitution of aromatic structures. The best correlation coefficients between vitrinite reflectance and different FTIR and NMR parameters were obtained when carbonyl/carboxyl versus;aromatic groups or chain length were considered in the correlations. Results related to the composition of bitumen and shale oil suggest that with increase in maturity the similarity of ens and shale oils increases.