To investigate the low-temperature oxidation characteristics of coal, programmed heating and oxidation experiments were conducted on single-particle-size coal samples from different mines. The inlet and outlet oxygen concentrations of the coal sample tank were measured to calculate the standard oxygen consumption rate (SOCR) of each coal sample at different temperatures. The relationship between the SOCR and temperature was fitted by an exponential function, and two regression coefficients (A and B) related to the spontaneous combustion characteristics of coal were obtained, and the effects of both A and B on the spontaneous combustion of coal was analyzed. The results show that the A and B values are related to the physical structures and chemical properties of coal, respectively. Accordingly, taking the A and B values of single-particle-size coal samples as the basic parameters, a new identification index describing the spontaneous combustion of coal is proposed. Compared with the chromatographic oxygen absorption method, the newly proposed identification index can reflect the degree of difficulty of spontaneous coal combustion more truly and intuitively. This research is of theoretical and practical significance for evaluating the characteristics of spontaneous coal combustion. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.