The devolatilization behavior of three bitumin-us coals has been investigated in an inert atmosphere under flash heating conditions using a micropyrolyzer/gas chromatographic technique. Coal particles were heated at various heating rates (up to 2 × 10⁴ K/sec). The yields of the product gas were determined in the pyrolysis temperature range between 773 and 1373 K. The effects of holding time and heating rate on the yields of the product gas were also considered. The yields of permanent gases drastically increase upon increasing the holding time and tend to reach their constant values. No appreciable increase was observed in the product gas yields upon increasing the heating rate over 5000 K/s. The yields of all the gas components increased with respect to temperature during these fast pyrolyses of coal. The yields of H₂, CO, and CH₄ appear to increase uniformly with temperature, whereas the yields Of CO₂ tend to level off above 1173 K in the present pyrolysis system. To predict the product gas yields, we evaluated several of the correlations in the literature with our present experimental data. The predictions are generally satisfactory from a relative simple correlation that describes the gas yield as a linear function of temperature with constants derived from derived experiment.