A bench scale experimental study was undertaken to investigate the potential of vacuum pyrolysis for the production of oil from Carboniferous-age oil shales from New Brunswick and Nova Scotia. Vacuum pyrolysis limits the secondary decomposition reactions, which as a result provides a high yield of pyrolysis oil and a low yield of gas. The objectives of this study were: (i) to determine the optimum pyrolysis conditions for the production of pyrolysis oil; (ii) to study the influence of reaction conditions on the nature of the oil; (iii) to correlate the oil composition with the organic source material; and (iv) to gain some insight into the kerogen decomposition. Batches of 120 g oil shale samples sieved to 1-5 mm particle size were heated to 600 degrees C and 1 kPa total pressure. The oil yield varied in the range of 10-20 wt% depending on the type of oil shale pyrolyzed. These oil yields are significantly higher than yields obtained by other industrial processes. The major pyrolysis gases generated during pyrolysis were CO2 (the most abundant), CO, H-2, CH4, and C-2-C-4 hydrocarbons. The pyrolysis shale oils were deasphalted and yielded about 60-80 wt% maltene. n-Alkanes with bimodal distribution in the range of C-8-C-34 were found in maltene fractions. The maltene fraction of a lamosite pyrolysis shale oil from New Brunswick was analyzed in detail. The analytical results were interpreted in terms of biological markers including n-alkanes, 2-alkylthiophenes, 2-alkylketones and triterpenoid hopanes. The soluble organic matter in the samples analyzed was found to be from a mixture of terrestrial and aquatic origins deposited in a lacustrine environment.