By the combustion of low calorific gases (LCG), a significant amount of primary energy can be saved and hazardous emissions can be reduced. However, the fluctuating composition, calorific value and high inert content of such mixtures result in technical difficulties concerning combustion stability. The intensive internal heat recuperation and the high flame stability of porous media burners offer great chances for LCG utilization. In this work, the combustion behaviour of LCG mixtures emitted from landfills and pyrolysis processes were investigated numerically and experimentally in the context of porous burners with SiC and Al2O3 porous structures. The adiabatic flame temperatures and the burning velocities were calculated using the GRI Mech. 3.0 with CHEMKIN tools in order to determine the possible operational conditions. In addition, a 3D numerical code was used to simulate the combustion processes in the porous burner. The influence of the combustion zone properties, the thermal load and the educt temperature were investigated. Experimentally, the operational range of the burners was specified at different power rates and different mixture temperatures.