Subaquatic oxidation of two bituminous coals by water-dissolved oxygen was investigated using batch reactor equipped with membrane oxygen sensor. Effects of time, temperature and coal grain size were studied as basic parameters influencing the oxidation process. Obtained results showed the subaquatic coal oxidation can be considered as interaction of the first reaction order with respect to oxygen. From temperature dependence of oxidation rate, activation energies E = 72 +/- 4 kJ mol(-1) and/or 50 +/- 4 kJ mol(-1) were calculated. For the samples, oxygen consumption R(O2) was found to be in the range of 2 x 10(-7) mol O(2) kg(-1) s(-1) to 6 x 10(-7) mol O2 kg(-1) s(-1), such values being quite comparable with R(O2) for aerial oxidation of bituminous coals. (C) 2010 Elsevier Ltd. All rights reserved.