Rapeseed oil was pyrolyzed in the presence of about 2% of calcium oxide up to a temperature of 450degreesC. A pyrolytic oil was produced that was narrow of diesel fuel. From the studies of ASTM distillation, the volumetric percentage of liquid in the same boiling range for diesel fuel was equal to 61% of the pyrolytic oil. The heating value of pyrolytic oil was 41.3 MJ/kg, which is equivalent to 93% of heating value of diesel fuel. The flash point was 80degreesC which is higher than diesel. This makes the pyrolytic product safer during handling and storage than diesel. In addition, thermally decomposed rapeseed oil was tested on a diesel engine and compared to diesel. The thermal efficiency (eta(th)) and brake specific fuel consumption were improved. The concentration of nitrogen oxides are less in the case of the produced fuel; this, in turn, reduced the formation of smog due to the presence of colored NOx. Moreover, the absence of sulfur in the pyrolytic oil is another advantage to avoid corrosion problems.