The transesterification of triglycerides contained in waste oilseed fruits with methanol has been studied in heterogeneous/homogeneous systems using acid and base catalysts. The acid catalysts (strong acid catalysts: USY, BEA, FAU-X, and weak acid catalysts: MCM-41 and ITQ-6 with Si/Al = infinity) were prepared by hydrothermal synthesis procedures. In order to obtain acid-base catalysts, potassium was loaded on different materials by ionic exchange (obtaining K-MCM-41, K-ITQ-6,). XRD, ICP-MS, IR after CO and CO2 adsorption, thermal analyses and N-2 adsorption/desorption techniques have been used for catalysts characterization. The highest triglycerides conversion and biodiesel yield values were achieved by K-ITQ-6 catalysts, after 24 h of reaction at 180 degrees C. Deactivation of this catalyst occurs for potassium leaching, but its regeneration and reuse are feasible and easy to perform. A possible continuous biodiesel production process has been proposed. (C) 2010 Elsevier B.V. All rights reserved.