Thermogravimetry with Fourier Transform Infrared Analysis (TG-FTIR) has been used to measure the organic oxygen content in a suite of coals of differing rank and compare these with the values determined by difference according to ASTM D3176-89. Two coking coals, one Cretaceous and one Carboniferous, were oxidized at 50 degreesC to simulate natural weathering and analyzed for their oxygen content by both techniques. Results indicate that the pyrolysis technique is reliable and rapid and is free of the large possible errors inherent in the determination of organic oxygen content by difference. (C) 2003 Elsevier Science B.V. All rights reserved.