A single cylinder diesel engine test facility and an air-aspirated spray burner facility have been modified and instrumented for studying diesel odor formation. Odor sampling and analysis techniques, based on the Arthur D. Little, Inc. Diesel Odor Analysis System (DOAS), have been developed and refined. Emissions mapping of the burner and the engine operating at steady state conditions, as well as transient engine conditions, are presented and discussed. The engine mappings presented indicate that operating parameters, such as injection angle, exceptionally high or low compression ratio, and exceptionally rich or lean air-fuel ratio, can have a significant effect on odor production. The burner results presented indicate that stoichiometry as well as combustion aerodynamics can strongly influence odor formation.