In the in-situ electromagnetic heating process some of the oil evolved during pyrolysis of Kerogen is lost to coking, cracking and combustion. An understanding of these decomposition processes is important in order to design appropriate technology to minimize them. Additionally, a mathematical description of these processes will enable realistic modeling of the oil shale. Combustion refers to exothermic chemical reactions of the gases. This process is controlled by the oxygen concentration present in the shale and is primarily a high temperature phenomena (T > 700/sup 0/C). Since such temperatures are not obtained in the electromagnetic process, combustion can be neglected. The Braun model (Braun, R. L., Mathematical Modeling of Modified In-Situ and Aboveground Oil Shale Retorting, Report No. UCRL-53119, Lawrence Livermore Laboratory, 1981) has been verified for heating rates of .0005 K/sup 0//S to .05 K/sup 0//S. This model should be valid for electromagnetic heating processes where the heating rate is about .0005 K/sup 0//S. Currently we are using this model in our numerical calculations, and the results will be presented in later reports. 4 references.