A household microwave (800W) was modified as a biodiesel reactor for continuous transethylation of waste frying palm oil. The high free fatty acid oil was simultaneously neutralized and transesterified with sodium hydroxide. With the ethanol to oil molar ratio of 12:1, 3.0% NaOH (in ethanol) and 30s residence time, the continuous conversion of waste frying palm oil to ethyl ester was over 97%. The waste palm oil biodiesel was then tested in a 100 kW diesel generator as a neat fuel (13100) and 50% blend with diesel No. 2 fuel (1350). The engine performance and emission are recorded. At the engine loads varied from 0 kW to 75 kW (at 25 kW intervals) of the maximum electrical rating, the performance of the neat and B50 are slightly lower than diesel No. 2 fuel. Emissions of NOx, CO and HC from B100 and B50 are lower than those of diesel No. 2 fuel, except that at the 75 kW engine load, where the B100 emits higher levels of NO than the diesel No. 2 fuel. (C) 2008 Elsevier B.V. All rights reserved