Abstract: A method for filtering and cleaning high temperature combustible gases, such as synthetic gas produced by a gasifier. The method involves introducing reactive lime to the hot combustible gas that has been previously cooled to less than approximately thirteen hundred (1,300) degrees Fahrenheit, and then filtering the gas through ceramic fiber filters to remove any particulate matter and the calcium salts resulting from the reaction of the lime with the chemical pollutants present within the gas. Optionally, reactive lime may also be introduced into the biomass feed as it travels to the gasifier.