High-temperature, short-contact-time pyrolysis of oil shales was investigated in our laboratory to gain a better understanding of the reaction mechanisms of kerogen decomposition. In order to accomplish this goal, the chemical composition of condensable materials and compositional differences between these materials and oils produced by low-temperature slow-heating processes were obtained. Analytical techniques that can analyze samples in microgram quantities, such as high performance liquid chromatography (HPLC), proton nuclear magnetic resonance (NMR) spectroscopy, field ionization mass spectroscopy (FIMS), and synchronous fluorescence (SF) spectroscopy were chosen for product characterization. Liquid chromatography was used in this work to separate shale oils into class types as well as in product characterization. Our work was in two phases. The first phase was on conventional oils. Here, HPLC as a tool for the separation of the aromatic fraction into subfractions according to the ring sizes and the possibility of using FIMS for a detailed compositional analysis of aromatic fraction of a fuel were investigated. The results were encouraging. The subfractions of the aromatic fraction were also analyzed using SF. The results of SF validated the HPLC separation procedure. In any case, the thrust of this research was to combine the results of several techniques to obtain meaningful and reliable characterization of oil shale pyrolysis products. This report covers the results obtained for oils produced by low-temperature slow-heating processes.