Combustion performance of premixed methane/air with hydrogen addition in a micro-planar combustor is numerically investigated, aiming to extend the application of various fuels in a micro-thermophotovoltaic system. The simulation results show that hydrogen addition has significant effect on raising methane reaction rate and flame stability. With the increase of hydrogen mass fraction, the location of the flame shifts toward the combustor inlet gradually, and the temperature gets a steady growth. For the micro-combustor with a channel height of 3 mm, it is found that the flame of pure methane is far away from inlet, which does not meet the basic working requirement of the micro-thermophotovoltaic system. However, the combustor wall temperature will be significantly improved when a small amount of hydrogen is added into the mixture, which is mainly due to the extension of flammability range. Along with the increase of H-2 addition ratio, both the total radiant energy and the proportion of usable radiant energy to total input chemical energy increase dramatically, which brings a significant improving of electricity output and system efficiency. (C) 2015 Elsevier Ltd. All rights reserved.