In this study, the effects of hydrogen peroxide on laminar. premixed. methane-air flames at atmospheric pressure and temperature were investigated using CHEMKIN III and GRI 3.5 mechanism. The range of fuel/air equivalence ratio (phi) was varied from 0.6 to 1.2. and the amount of hydrogen Peroxide was altered from 0% to 20% volumetric fraction. of the methane-hydrogen peroxide (air excluded) mixture. The burning velocity was found to increase with increasing hydrogen peroxide addition. with a relatively larger increase for the fuel-richer mixtures (DeltaS(u) up to 15 cm/s for phi phiapproximate to 1.2). The adiabatic flame temperature rose with hydrogen peroxide addition, and the temperature rise per unit hydrogen peroxide addition was more significantly (AT up to 100 K) for the leaner mixtures. For the same mixture stoichiometry, adding hydrogen peroxide also increased CO concentration and N2O emissions somewhat. Accordingly, the benefits of adding hydrogen peroxide to the combustion conditions considered here can be best realized by burning leaner mixtures. (C) 2004 Elsevier Ltd. All rights reserved.