Surface stabilized combustion is fuel flexible technology that extends lean stability limits, widens the operation range of lean premixed systems, and is able to achieve ultra-low NOx emissions< 10ppmdv. The technology has been widely used for natural gas fired devices including domestic boilers, radiating heaters, dryers, etc. One distinctive characteristic of the surface stabilized combustion is the extended volume of the reaction. The volume ratio of surface flame over a jet flame can be~ 50 times the volume of the thin flame front of a jet flame (for the same firing rate). This characteristic gives the surface stabilized burner increased direct radiation heat from the flame to the load. The heat transfer from the flame to the nearby surface cools the reaction which helps favors ultra-low NOx emissions. While these attributes are well established for natural gas, stability limits and emissions of the burner when running on variable fuel composition has not been previously reported. The present work explores the effect of the fuel composition on stability and emissions. Natural gas and three biogas blends at constant firing rate, atmospheric pressure and without air preheating are studied. The results show that addition of CO2 to the fuel improves the radiation properties of the flame as its absorption coefficient is 5 times higher than the water coefficient. The burning modes of the burner are characterized according to the ratio of the velocity of the gases exiting the surface over the laminar burning velocity. The experimental results indicate that the radiant mode is established at a velocity ratio higher than 1.4. Since for the most diluted biogas by volume (65% CO2/35% CH4) this ratio is always higher than 2, the burner does not attain the radiant mode operation for this fuel type. The burner is able to burn this wide array of fuel compositions without any modifications.