The goal of this research is to determine the feasibility of a catalytic compression-ignition engine running on aqueous ethanol fuel. A naturally aspirated, three-cylinder, direct-injection diesel engine manufactured by Yanmar has been modified to operate as a homogeneous-charge, compression-ignition engine. This involved removing the fuel injectors, replacing them with catalytic elements located inside a small pre-chamber, and installing a pulse width modulated fuel injection system. The fuel is 35% water and 65% ethanol by volume. The catalytic igniters allow the engine to operate continuously at various load levels corresponding to a broad range of air/fuel ratios. To adjust ignition timing and monitor in-cylinder combustion, the engine has been instrumented with a piezoelectric pressure transducer and a crankshaft encoder. Pressure traces are quite repeatable from cycle to cycle and resemble combustion patterns in typical Otto cycle engines. This catalytic engine concept represents an attractive paradigm for clean engine development.