Abstract Bituminous coal samples from La Jagua Colombia were oxidized in air at 150 and 200°C during 6, 12, 18, and 24 hours. Fourier transformed infrarred (FTIR) thermogravimetry and ultimate analysis showed that the oxidation increased oxygenated groups and decreased aliphatic and aromatic structures of coal. The oxidation effects were greater at the higher temperature of 200°C and significant up to the first 12 hours. Oxidation also affects the devolatilization process, as the oxidized sample shows a lower volatile evolution than the raw coal, which indicates that during the oxidation there is an early volatile evolution. This result is very good because it shows that La Jagua coal can be used for activation as subsequent process. Keywords: Atomic ratioDifference spectraOxidationOxidation index Acknowledgments The authors wish to thank the Universidad Nacional de Colombia and CONA-CYT Mexico for financial support of this work. Notes b Dry ash free. d Dry. S = Specific surface area.