The dilution effect of carbon dioxide (CO2) in an oxidizer was studied experimentally in a non-premixed oxy-methane flame. A lab-scale furnace with a slot-type burner was used as a model of an industrial furnace. The objectives of the current study are to investigate the flame stabilization, to analyze the flame spectra, and to study the flame behavior of non-premixed oxy-methane flames as the CO2 mole fraction is varied in an oxidizer. The flame stabilization was estimated by changing the flow velocity at the fuel jet nozzle exit (u(F)) and the oxygen nozzle exit (u(Ox)) from u(F) = 7-50 m/s for methane (CH4) and from u(Ox) = 10-120 m/s for oxygen (O-2), respectively. The experimental results indicate that the flame stabilization of non-premixed oxy-methane flames decreased with increases in the CO2 mole fraction in the oxidizer. The flame spectra of non-premixed oxy-methane flames had a maximum intensity at the wavelength (lambda) of lambda = 308 nm. The reaction zone of non-premixed oxy-methane flames was broadened by the addition of CO2 to the oxidizer. (C) 2013 Elsevier Ltd. All rights reserved.