In this article, we investigate the combined effects of emission of CO2 and O2 depletion on thermal stability in a long cylindrical pipe of combustible reactive material. The cylindrical pipe loses heat by convection and radiation at the surface, and the nonlinear differential equations governing the heat and mass transfer problem are tackled numerically using Runge–Kutta–Fehlberg method coupled with shooting technique. The effects of various thermo-physical parameters on the temperature, CO2 and O2 fields, and thermal stability are presented graphically and discussed quantitatively.