Organic nitrogen plays an adverse role in the utilization of oil shale, deactivating catalysts in the shale oil refining process and forming NOx in the combustion of oil shale and shale oil. To have a deep understanding of its thermochemical transformation during the decomposition of oil shale, the conversion of organic nitrogen is experimentally studied and a set of physical models of nitrogen-containing groups is constructed and solved using the quantum chemical transition state theory (TST) in the Gaussian 09, Revision A.02 package. The results obtained show that three principal nitrogen-containing species pyrrolic nitrogen, pyridinic nitrogen and amino nitrogen.first crack to nitriles or amino species from the breakup of the C N bond, and then to HCN and NH3. If attacked by oxygen containing groups, the nitrogen-containing products formed can be further converted into NOx. Including also quaternary and chemisorbed NOx in the study, the conversion history of.five typical nitrogen-containing groups present in oil shale kerogen is summarized and illustrated.