The search for alternative sources of energy is more important than ever as the extraction of petroleum, the greenhouse gas emissions and the climate changes are getting extremely complicated an unsafe for mankind. In order to find renewable, cheaper and easier methods to obtain energy, a hydrocalumite-type compound was synthesized by a green method here presented and evaluated in the transesterification of castor oil with methanol to obtain biodiesel. The pristine material and its thermally decomposed products were analyzed by X-ray powder diffraction, thermogravimetric analysis and Scanning Electron Microscopy. Biodiesel conversion was determined by H-1 NMR. The effect of the precursors' thermal activation on biodiesel production was evaluated at 300, 500 and 700 degrees C. Similar results were obtained with the solids produced by a conventional method, demonstrating that the materials prepared by the new technique disclosed not only comparable physicochemical properties, but also analogous catalytic activity; revealing the feasibility of producing high active catalyst's precursors by a simple, economic and environmentally-friendly method. (C) 2012 Elsevier Ltd. All rights reserved.