The invention concerns a two-stage method for the reutilization of used frying oils. The first stage involves a method for purifying the used frying oils by carrying out several sequences of basic operations involving filtering, centrifugation and/or absorption treatments. This stage by itself makes it possible to reduce environmental deterioration in the sector due to the dumping of said residual oils and simultaneously provides raw materials for processing in a second stage. The second stage involves reutilization of the materials obtained from the first stage for utilization as raw material in transformations and/or biotransformations with the purpose of obtaining high value added industrial products such as surface active agents, biofuels, additives for cosmetics, lubricants, food products or hydraulic fluids.