Combustion performance of a blend containing 20% soybean methyl ester in heating No. 2 fuel was examined using a residential-scale hot water boiler. The blend burned satisfactorily with no modifications to the appliance and fuel delivery system. SO2 emissions were 19.7 +/- 2.5% lower than that of No. 2 fuel while NOx emissions were similar. Particulate emissions, as determined by a source dilution measurement system, were on average 15.7 +/- 7.5% lower than that of No. 2 fuel. The particulate bound sulphates were also lower by 14.1 +/- 6.1%. Results indicate potential reductions of PM2.5, SO2 and greenhouse gas emissions for the petroleum distillates that can be replaced with biofuels. Reduction of sulphate in PM2.5, which is associated with adverse health effects, is considered significant. Crown Copyright (C) 2004 Published by Elsevier Ltd. All rights reserved.