The chemistry and decomposition dynamics of oil shale are reviewed with the aim of defining a preliminary model characterizing the yield of oil from Atrium shale. Data on oil shale decomposition taken over a period of nearly three decades are summarized and caste into a model for the decomposition kinetics. Few order rate constants, drawing heavily from the detailed studies of Johnson, et al., are suggested as input to numerical model calculations. Since many of the decomposition reactions have large activation energies, the importance of quantifying an accurate thermal history in the shale during the decomposition is underscored.