Volatile organic compounds (VOC) and soot particles have been determined in a Diesel＇s exhaust gas. A new sampling method allowed the measurement of emissions of organic compounds (C-1 to C-20) in a gas chromatogram at a detection limit of ca. 0.2 mg/m(3). Particles were collected with a filter bed of ceramic particles and characterized by temperature programmed desorption (TPD) and oxidation (TPO). Engine runs were always performed at a fixed and constant air to fuel equivalence ratio (lambda) and with a constant volumetric efficiency, because these parameters strongly influenced the emissions in terms of both composition and order of magnitude. The effective combustion temperature again strongly governed the nature of the emissions. Model fuels, composed of individual paraffins and aromatics and additions of sulfur compounds and an organic nitrate (for cetane number enhancement) were used. The results contribute to the understanding of the origin of specific emissions from Diesel engines. These newly developed methods are recommended for further application.