Fossil fuel contributes 80% of the word’s energy needs. Whereas, the emission produced by the emission of fossil fuels contribute to air pollution and global warming. Biodiesel as one promising alternative to fossil fuel for diesel engines has become increasingly important due to environmental consequences of petroleum-fuelled diesel engines and the decreasing petrol resources. The aim of the current study is to investigate the effect of Soyabean oil blended with “Diesel fuel” on the existing engine emissions. In this study, biodiesel was produced by transesterification of soyabean oil with methanol using sodium hydroxide (NaOH) as catalyst which was blended with diesel. The ratio of diesel to soyabean oil that was used were; 80% diesel-20% soyabean oil (B20), 60% diesel-40% soyabean oil (B40), and 100%diesel-0% soyabean oil (B0). The study revealed that soyabean oil can be processed into biodiesel through transesterification. Soyabean biodiesel blends produced lower CO, HC, and CO2 emission than diesel fuel while emission of NOx from soyabean biodiesel fuel were found higher than NOx emitted from diesel fuel.