In integrated gasification combined cycles systems, it is of interest to estimate the burn or gasification rate (m), particle surface/wall temperature (T-w), and flame temperature (T-f), and also control of the T-w and T-f with free stream CO2 and the H2O level, which promote endothermic reactions. In the past, char combustion in the air was modelled using either a conventional single film model (SFM), or a conventional double film model (DFM). In this study, modified SFM and DFM models, including both heterogeneous reactions of CO2 and H2O with C, and gas phase oxidation of both CO and H-2, were developed. The SFM and DFM were switched to SFM-DR (single film model with double reactions) and DFM-DR (double film model with double reactions). The SFM-DR assumes that the gas phase is frozen, with the final products being CO and H-2, and the transfer number modified to B=YO2,infvO2,I+YCO2,infvCO2,III+YH2O,infvH2O,IV; DFM-DR includes gas phase oxidation of both CO and H-2 with O-2, with the final products being CO2 and H2O and the same modified transfer number B under infinitely fast chemistry. Finally, six different char combustion cases with or without H2O and CO2 in the free stream were simulated to obtain the flame profile for modified SFM-DR and DFM-DR. It was found that reasonable flame profiles of char combustion were obtained for both SFD-DR and DFM-DR. Moreover, the O-2-rich combustion could promote the endothermic Boudouard and steam-carbon reactions. Finally, the burning rate (kg/m(2) center dot s) decreased with the increase of particle diameter for both SFM-DR and DFM-DR.