An inboard marine engine was tested on a dynamometer for exhaust emissions. This paper gives some insight into the characterization of baseline emissions for a new marine inboard engine as well as potential emission reductions through the use of oxygenated fuels. As the percentage of alcohol in the fuel increased, HC and CO decreased and Nox increased without a significant change in power. Fuel consumption also increased slightly.In addition, the sensitivity of the test cycle on exhaust emissions was investigated using four transient and two steady-state cycles. Only HC seemed to be affected by the amount of transience added.