"The proton and carbon-13 NMR studies were made on the saturates, olefins, and aromatic fractions obtained from the naphtha and light distillate cuts of in situ shale oil. Carbon-13 NMR area measurements were used to compute the C/C ratio and, thus, the average paraffinic chain length for the saturate fractions. Identification and the relative concentrations of the various olefins were determined from carbon-13 NMR data. The NMR results are compared with the mass spectroanalysis data on the same fractions. The percent of carbon types in the aromatic fractions were also determined by both NMR and mass spectral data . Qualitative agreement between the two techniques was evident. However, some definite disagreement also exists."