This paper presents the results of an experimental investigation of combustion characteristics of nonswirl CH4/CO2/O-2 flames under atmospheric pressure in a lean-premixed multihole burner's gas-turbine model combustor. The CO2 and O-2 are well premixed and then channeled to a test rig, which is made up of a 2 in. diameter 1 m long pipe to premix the fuel and oxidizers before getting to the multihole burner. The burner consists of main holes and subholes that prevent flashbacks that may lead to rig explosion. The burner imparts jet to the premixed measured composition of CH4/CO2/O-2. The results indicated that the adiabatic flame temperature (T-ad) is a strong controlling parameter in quantifying the stability map and combustor flame shape; variation in oxygen fraction and equivalence ratio influence the flame shape, whereas the equivalence ratio (phi) is the major controlling parameter of temperature distribution within the combustor. The results also indicated that the stability map does not follow the lines of constant power density, mass flow rate of the mixture (m(mix))over dot, and Reynolds number (Re).