Gasification of municipal solid waste was performed with double normal diffusion flame (DNDF) burner (existing technology) and a newly developed double inverse diffusion flame (DIDF) burner, using a process based on Thermoselect. The DIDF and DNDF burners were first optimized for radiation heat flow by changing the ratio of primary oxygen (PO) and secondary oxygen (SO). PO:SO ratios of 3:1 and 1:1 were determined to be the optimum ratios for the DIDF and DNDF burners, respectively. The radiation heat flow for these PO:SO ratios were 56.6 and 36.8 mW for the DIDF and DNDF burners, respectively. The flow rate of slag was also higher (94%) for the DIDF burner than for the DNDF burner (88%). Gasification with the DIDF burner also yields less fly ash and has been determined to be more energy efficient than that with the DNDF burner.