The application of wet forward combustion requires reliable kinetic data for the chemical reactions occurring during process. The presence of water in injected air seems to have a significant effect on the process. This study was conducted to investigate the effect of water on combustion reaction kinetics in limestone packs containing heavy oils where simultaneous injection of air and water was realized. During this work, experiments were conducted in a reaction kinetics cell made of stainless steel. Five different crude oils from Turkish oilfields were investigated. In all experiments, water (0.35 cc/min) was simultaneously injected with air (1.5 lt/min). Linearly increasing temperature at a rate of 1 degrees C/min was used and reaction products Of CO2, CO, and O-2, and temperature were recorded continuously Arrhenius constant, relative reaction rates, activation energies were determined using reaction kinetics model. Results showed that partial pressure of oxygen had on effect in reaction parameters and considerable difference existed when comparison is made with experiments where only air was used. Product gases, CO2, CO, and O-2 were lower when water was present. The logarithmic relationship between atomic H/C and temperature was observed however the constants of the equation were lower in simultaneous air-water injection. At higher temperatures where fuel combustion reaction occurs, activation energies were higher when water was present. For low temperature reactions, activation energies were lower.