A fixed-bed reactor was used to pyrolyse small samples of oil shale particles under an inert gas flow (argon). A special sampling technique was used for collecting organic products eluted from the reactor at different temperatures and time intervals. The pyrolysis products were analysed by capillary gas chromatography and the total product evolution rate was investigated as a function of temperature and time. The maximum volatile product evolution temperature was similar to 440 degrees C. The aliphatic hydrocarbon content of the pyrolysis products was characterized and classified by carbon number. In addition, the performance of the experimental system was assessed by a carbon balance. The recovery of total organic carbon as organic volatile products, CO2 and coke was determined.