Sulfuric acid production from sulfur-based acid plants and smelters is analyzed. Industry competition, with particular emphasis on voluntary versus abatement acid, is reviewed. Regionally, even though smelter acid is geographically limited, competition is at least moderate. Production costs for both acid and smelters are estimated. Due to the byproduct nature of the latter, assigned costs and acceptable producer price are much the lowest. Large- scale users will prefer sulfur-based acid production if the heat value of the reaction can be utilized as a steam credit. Additionally, voluntary acid is a more stable supply source than smelter acid. Voluntary acid output is a reaction to price and demand conditions. Abatement acid production depends on apc implementation and the state of the relevant metals markets. Even if copper, lead, and zinc output remains at current levels, if current EPA regulations are implemented, acid output will approximately double. An output forecast is made based on apc regulations, implementation, and estimated metals production. As a direct competitor to U.S. acid and as indirect competitors to Frasch sulfur, Canadian and rest-of-world acid output is reviewed.