The objectives of this study are to investigate the effect of diesel fuel blend with n-butanol on the emission of turbocharged common rail direct injection (CRDI) diesel engine and to compare the results with the neat diesel fuel operation case. The blends considered here were blends of diesel fuels with 10% and 20% (by volume) n-butanol. Engine performance and emission characteristics were measured by the European Stationary Cycle (ESC) test. Emissions of HCs, CO, NOx, HCHO, HCOOH and NH3 were measured by Fourier Transform Infrared Spectroscopy (FTIR). Size and number distribution of particulate matter (PM) were measured by the Scanning Mobility Particle Sizer (SMPS). From the results, for the n-butanol blend, NOx emission increased compared with the neat diesel fuel case. At the case of 20% butanol, both THC and CO emissions increased significantly, and both HCHO and HCOOH increased modestly under the low loading of ESC 7, 9 and 11 mode compared with the neat diesel fuel case. Higher blending ratio (>20%) of butanol fuels could contribute to the precursor of PAHs formation such as toluene and benzene in diesel combustion. BUS blend could be a better option to reduce the PM mass and the emissions of nanosized PM under 50 nm. (C) 2015 Elsevier Ltd. All rights reserved.