A model is presented to predict turbulent non-adiabatic premixed combustion of methane under gas turbine conditions. Chemical reaction and heat loss are described with four independent scalar variables. These are the enthalpy variable and three reaction progress variables for combustion of methane, hydrogen and carbon monoxide. In the combustion model turbulence is taken into account by weighting with an assumed shape PDE The model is used to calculate a 32 kW methane flame in an air cooled combustion chamber. The calculated CO, CO2, O-2 and NOx concentrations are compared with suction probe measurements at several locations in the combustion chamber. The non-adiabatic calculations and the measurements show good agreement. Adiabatic calculations show a significant overprediction of NO. Radial profiles of mean axial velocity and turbulent kinetic energy were measured with a 2D LDA system. The measurements show a good agreement. It is concluded that the non-adiabatic model is necessary and suitable to predict NO formation in turbulent premixed methane flames with heat loss.