An entrained reactor system (LFER) has been used to study the rapid pyrolysis kinetics for both eastern (New Albany) and western (Colorado) oil shales. Under the condition of high heating rate, a fundamental understanding of the product quality/composition was obtained. Flow visualization and temperature characterization in the LFER were conduced to provide a critical laminar flow and isothermal reaction zone. Calibration curves depicting the flow regimes confirmed that the existing inlet and reactor design can be operated without particle dispersion caused by turbulence. Rapid pyrolysis was carried out in nitrogen at 700{degree}, 750{degree}, 800{degree}, and 850{degree}C. For each temperature, the sampling probe was set at five or six different positions along the length of the reactor tube to obtain different particle residence times. The weight loss (or cumulative yield) was determined by using the ash tracer technique and the organic conversion rate was modified from dry ash free basis to dry mineral matter free basis. A single particle model was developed to evaluate the particle velocity/temperature-time profile and a pyrolysis kinetic model based on the first-order Arrhenius Law was developed to calculate the kinetic parameters. The global kinetic parameters for both oil shales were determined and some main factors affecting on the process were determined. 43 refs., 86 figs., 10 tabs.