Four bituminous coals of the same rank but with different thermoplastic properties were oxidized at 40 and 50 degrees C for one month. The chemical changes due to oxidation were studied by applying Gieseler plastometry, the free-swelling index (FSI), thermogravimetric analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In general, oxidation at 50 degrees C produced a greater impairment of coking properties, the different responses to oxidation depending on the parent coal. The main effects caused by oxidation were a loss of thermoplastic properties, a decrease in aliphatic hydrogen and a slight increase in groups with oxygen functionalities. Both the fresh and oxidized coals were carbonized in a movable-wall oven of 17 kg capacity and the quality of the resulting cokes was tested by means of the JIS and ASTM standard methods. The results showed that, in certain cases, mild oxidation produced an improvement in coke quality. Oxidation also affected the porosity of the cokes, which may be related to the coke quality. It was found that the higher quality cokes had less macroporosity, whereas the lower quality cokes had a higher pore volume. (C) 2016 Elsevier Ltd. All rights reserved.