Advances in engine technology in recent years have led to significant reductions in the emission of pollutants and gains in efficiency. As a facet of investigations into clean, efficient combustion, the homogenous charge compression ignition (HCCI) mode of combustion can improve upon the thermal efficiency and nitrogen oxides emission of conventional spark ignition engines. With respect to conventional diesel engines, the low nitrogen oxides and particulate matter emissions reduce the requirements on the aftertreatment system to meet emission regulations.In this paper, n-butanol, an alcohol fuel with the potential to be derived from renewable sources, was used in a light-duty diesel research engine in the HCCI mode of combustion. Control of the combustion was implemented using the intake pressure and external exhaust gas recirculation. The moderate reactivity of butanol required the assistance of increased intake pressure for ignition at the lower engine load range. The upper load range was limited by the excessive pressure rise rate at a modest engine load. Within this possible load range, an analysis of the hydrocarbon species in the exhaust was performed using Fourier transform infrared spectroscopy to gain insight into the combustion characteristic of butanol in HCCI. A comparison is made with gasoline fuel to compare the reactivity of butanol in this pair of high volatility fuels.