This article presents the results of the comparison of two experimental studies to obtain biodiesel from castor and sunfl ower oils. During the development of the projects a standard methodology was adopted that defi ned the physical and chemical parameters of the biodiesel as a sunfl ower and Castor oil originated biofuel. To obtain a comparative model and maximize the performance of castor and sunfl ower oils, the NTC 100/04 standard was chosen, using the mix ratio 5, 10, and 20%, respectively, of biodiesel. Complying with the NTC 100/04 standard, the recommended parameters were followed in the tests performed to compare the results obtained. The methodology chosen allowed assessing the behavior of the combustion gases to achieve the final combustion composition, as well as the development of a comparison between the two biofuels with the fossil fuel (pure diesel) used in diesel engines in Colombia. This study was carried out in Bogotá (2600 m above sea level), and as a result there was a slight decrease in CO2 and CO output of combustion gases comparing the pure ACPM (oil fuel for engines) and the Biodiesel, for the various mixtures proposed under the ICONTEC norm.