A method and apparatus for conversion of solid and liquid fuels to a synthesis gas, steam and/or electricity in which about 10% to about 40% of a solid fuel and/or a liquid fuel is introduced into a gasifier and gasified, resulting in formation of a synthesis gas. The remaining portion of the solid fuel and/or liquid fuel is introduced into a first stage of a multi-stage combustor, resulting in formation of products of combustion and ash and/or char. The synthesis gas is introduced into a second stage of the multi-stage combustor disposed downstream of the first stage and overfire oxidant is introduced into a third stage of the multi-stage combustor disposed downstream of the second stage. The ash and/or char from the multi-stage combustor is then recycled into the gasifier.