The study of physicochemical properties of solid catalyst such as particle size, surface area and basicity are significant today since their reactivity depend on these properties. The number of defect sites in CaO, an alkaline metal oxide is important in heterogeneous catalysis. In this research work, nanostructured CaO was synthesized from commercial CaO via hydration-dehydration method. The surface modified CaO was calcined at various temperatures from 300°C to 800°C respectively under vacuum atmosphere of 10-3mbar. The prepared nanostructured CaO was then characterized using Thermogravimetric Analysis (TGA) and Fourier Transform Infrared (FTIR). The basicity then determined by back titration method. This research found that when activation temperature increased, the basicity also increases. For optimization, the prepared nanostructured CaO-600 was selected and applied for base transesterification reaction using algae species, Kappaphycusalvarezii to produce biodiesel. The latter reaction was then confirmed by Nuclear Magnetic Resonance (NMR) spectroscopy.
