This paper presents a numerical simulation of oxygen-hydrogen high pressure (up to 15 bar) spray combustion within a cylindrical chamber. The numerical simulation is based on a finite volume approach. The effect of pressure and wall temperature on the combustion characteristics such as temperature distribution, rate of reaction and flame position are studied and a brief conclusion is presented. Results showed that the flame temperature decreases with pressure, where the effect of pressure on the shape and position of the flame depends on flow parameters and combustion characteristics. This effect, discussed in this study, can be different at various pressures. It is shown that flame temperature and rate of reaction reduce as the wall temperature decreases.