Biodiesel is a highly effective fuel with the same efficiency such as diesel oil derivative only accompanied by moderate engine modifications. This type of biofuel can be obtained from renewable sources such as vegetable, animal or frying oils. In this context, waste frying oils transesterification was studied to obtain the maximum value of biodiesel. Transesterification reactions were carried out between 70 to 90 min using waste frying oils (WFOs), methanol, and sodium hydroxide as catalyst. In order to determine the best conditions for biodiesel production, a series of experiments were carried out, using catalyst percent and temperatures in a range of 0.16 to 1.84% and 40 to 90°C, respectively. The highest biodiesel production was obtained using catalyst percent, temperature and reaction time of 0.5%, 80°C and 90 min, respectively. By statistical experimental design was possible to determine a mathematical model to predict the best operational conditions to maximize biodiesel production.