The model of porous particle combustion is developed. The equations of heat and mass transfer are considered both inside and outside the particle. The model takes into account the heterogeneous reactions inside the porous and homogeneous reaction outside the particle. Heat losses by radiation are taken into account also. The boundary of domain, where the dependence of the rate of the particle combustion rate on particle temperature is existed, is determined. Two regime of the particle are possible: high-rate regime for the porous particle with high internal surface and low regime for the particle with low internal surface. In high-rate regime the reaction of carbon with oxygen is occurred in layer at the particle exterior. Carbon monoxide is formed in the heterogeneous reaction of carbon with oxygen in high-rate regime. In low-rate regime the heterogeneous reaction of carbon with oxygen is occurred in whole volume of the particle. Both carbon monoxide and carbon dioxide are formed in low-rate regime of the particle combustion. Analysis of the model gives the possibility to determine the kinetic equations of the heterogeneous reactions 2C + O2 = 2 CO if the kinetic equations of the reaction C + CO2 = 2 CO is known.