The purpose of this study is to evaluate catalysts suitable for the reduction of particulate emissions from heavy duty diesel engines over the European R49 cycle.Catalyst formulations were screened in a laboratory reactor in order to select promising candidates for further evaluation in test engines. The approach was to evaluate different support materials in relation to storage of sulphates and the optimisation of precious metal loadings with promotors and inhibitors. The objective was to obtain the optimum balance between gaseous activity and particulate control.Catalysts selected from the screening process were installed on a test bed engine. Emissions were measured over the European R49 test procedure, to determine the effect of fuel properties on catalyst efficiency and exhaust emissions. The test engine was selected to represent the technology used to meet Euro 1 emissions standards (1992/3).The catalyst performance was evaluated against the following fuel parameters: sulphur and cetane number.The optimum catalyst gave a 19 per cent reduction in particulate emissions and was insensitive to the sulphur content of the fuel up to 500ppm. All selected catalysts reduced hydrocarbon and carbon monoxide emissions by over 70 per cent, but had no effect on oxides of nitrogen emissions.