The invention can be summarized as follows. There is provided a method for oxidizing elemental mercury in a combustion process comprising, adding a composition comprising an aluminum silicate to a combustion chamber, boiler or kiln downstream from the burner region combustion zone. There is further provided a method for reducing the emission of one or more heavy metals in a combustion process by adding a composition comprising an aluminum silicate to a combustion chamber downstream from the burner region combustion zone. There is also provided a composition comprising an aluminum silicate that may be employed to oxidize elemental mercury generated in a combustion process. The composition also may be employed to reduce the emission of one or more heavy metals generated in a combustion process.