Much work is reported in the literature pertaining to premixed burners using hydrocarbon fuels. However, very little work is available oil similar burners using producer gas as a fuel. The present work aims at testing and optimization of a premixed burner with producer gas as a fuel. A burner of 150 kW capacity is used in the experimental investigations. The burner is of concentric tube type fully premixed in which air is supplied through central pipe and gas is supplied through annular passage. Swirl vane is provided to air and gas for thorough mixing. The bluff body is provided for flame stabilization. The premixed burner was tested on open core throat-less down draft gasifier for flame quality. A stable and uniform flame was observed with this premixed burner. Thereafter, an instrumented test set up to evaluate burner performance was installed oil an open core gasifier. The burner was experimentally optimized for size and location of bluff body and flammability limits. The burner was optimized by using bluff bodies of 46, 61, 73, 80, 85, 98, 110 and 122 nun diameters. The burner was operated in batch operation of 6-8 h for optimization of various parameters. The experiment reveled that the uniform and high-temperature premixed flame was observed at conventional bluff body having blockage ratio of 0.65. The flammability limits for producer gas fired burner was established in the range of 40-55. (C) 2007 Elsevier Ltd. All rights reserved.