A test program was initiated to characterize exhaust gas emissions from an automobile equipped with a dual catalyst system. The dual catalyst system was designed by Gould, Inc. to reduce emissions of engine exhaust hydrocarbons, carbon monoxide, and nitrogen oxides. It basically consists of two catalysts in series: a nickel-copper alloy reduction catalyst to control nitrogen oxide emissions, and a platinum-palladium oxidation catalyst to control carbon monoxide and hydrocarbon emissions. The test vehicle, an AMC Hornet having a 232 CID six cylinder engine, was tested over the Federal Test Procedure, the Highway Fuel Economy Test, and the Sulfate Emission Test. In addition to the regulated gaseous emissions, sulfur dioxide, sulfuric acid, hydrogen cyanide, nickel carbonyl, carbonyl sulfide, aldehydes and detailed hydrocarbon emissions were sampled and analyzed. A brief discussion of each method used to sample and analyze the non-regulated pollutants is included. Results indicate that (1) sulfate emissions from the dual catalyst car were comparable to those from production catalyst vehicles equipped with air pumps, (2) hydrocarbon emissions were of low reactivity relative to other vehicles, and (3) nickel emissions were quite high. With regard to the nickel emissions, the forms in which this element are emitted are not known nor is the extent of nickel carbonyl emissions known.