Non-catalytic partial oxidation of natural gas/O-2/H2O mixture at elevated pressures was simulated kinetically using Chemkin package incorporating detailed reaction mechanisms of methane oxidation. The dependence of reaction time was investigated as a function of inlet temperature, system pressure, and O-2/CH4 ratio. The conversion to products was predicted to complete within a residence time of less than 0.1 ms at pressures greater than 30 atm and temperatures higher than 1450 K. A minimum O-2/CH4 ratio of 0.64 was found necessary for a complete methane conversion at the conditions typical for the industrial reformer. The effect of O-2/H2O in the feed gas was examined computationally, and the results suggested that adding H2O in the feed gas could be a viable tool for adjusting the H-2/CO ratio in the products and for controlling the flame temperature. Formations of higher order hydrocarbons and soot, which may play important roles in the actual fuel-rich conversion environment, are not considered in the present study. (C) 2009 Elsevier B.V. All rights reserved.