Lipases are enzymes that have an important role in the industry for their wide use, giving rise to a great interest in industrial bioprocesses due to their versatility. One of the applications is the enzymatic hydrolysis of waste oils. This work consists of evaluating the production of lipases using several concentrations of residual frying oil (RFO) and different pHs, through ANOVA analysis. The production of free fatty acids was carried out by hydrolysis of RFO using noncommercial lipases produced in the previous step. The production of lipase enzymes was favored at pH 2.0, with an oil concentration of 1.5% (v/v) for a period of 24 hours, resulting in an enzyme activity of 141.90 U. mL-1 . The highest result of enzymatic hydrolysis of RFO was 20.70% in 40 minutes. This conversion was favored by increasing the concentration of the enzymatic extract. In this study, it was possible to obtain free fatty acids (FFAs) using a noncommercial enzyme and waste oil as an environmentally correct and low-cost alternative.