This report has been prepared to provide reliable information on atmospheric emissions from sulfuric acid manufacturing plants and on methods and equipment normally employed to limit these emissions to satisfactory levels. Background information is included to define the importance of the sulfuric acid industry in the U.S. Basic characteristics of the industry are discussed, including growth rate in recent years, types of raw materials used, end uses for the product, and the number of producing establishments, i.e. manufacturing sites, in existence during the past and at the present time. Process descriptions are given for the two processes in commercial use; the contact process and the chamber process. The emission data represent results from approximately 12% of the present number of establishments. Most of these data have been gathered from production records of sulfuric acid producers. The data also include results from several stack-sampling programs conducted jointly during 1963 by the Manufacturing Chemists' Association and the United States Public Health Service.