The present invention relates to the reduction or inhibition of corrosion in an atmospheric burner unit by adding to a combustion system an effective amount of manganese, or a manganese precursor source, or derivative. The system may further include a catalyst package that may be composed of one or more individual organometallic compounds of Li, Na, K, Mg, Ca, Sr, Ba, Mo, Fe, Co, Pt, Ce, and combinations, mixtures or precursors thereof. The manganese component of the catalyst package of the present invention reduces or eliminates the poisoning of the combustion system, whereby improved combustion and reduced emissions result. In addition, this invention inhibits both high- and low-temperature corrosion that occurs on the hot surfaces of burner furnace walls and tubes, and on cooler surfaces of the burner unit exhaust stack.