One of the major impacts that humans have had on the world is the consequence of the use of natural resources of the planet, whose purpose has been the energy supply for economic and technological development. This economic development has caused an increase in the demand for goods and services in industrialized countries, and in turn has led to an increase in per capita consumption of energy worldwide. For this reason, it is very important to develop new energy alternatives to reduce the actual dependence on petroleum and, at the same time, reduce the impact of emissions of greenhouse gases to the environment. An alternative to using fossil fuels is biodiesel, which is biodegradable, eco-friendly, and represents an economical source of energy. Biodiesel may be produced by the transesterification reaction of new or used vegetable oils (for example sunflower, corn, or olive oil) with a short chain alcohol (methanol) in the presence of a catalyst (NaOH). In the present work we have synthesized biodiesel from these three types of vegetable oils that have been subsequently characterized. Different chemical tests have been used to ensure the quality of the biodiesel obtained. The results indicate that sunflower oil provided better efficiency biodiesel, followed by corn and olive oils. CO2 emissions that could affect the environment were, in all cases, less than 4.1%.