[en] Highlights: • Porous CaO was prepared via PSS-induced mineralization followed by calcination. • The as-synthesized porous CaO catalyst showed a much enhanced catalytic activity. • Strong basicity and porous structure of the catalyst led to desirable performance. - Abstract: In this study, a porous CaO-based catalyst was synthesized using a fast mineralization process induced by sodium poly (styrenesulfonate) (PSS) followed by calcination. The solid base catalyst was tested in palm oil transesterification to determine its viability in biodiesel production. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N_2 adsorption/desorption, temperature programmed desorption of CO_2 (CO_2-TPD) and energy dispersive spectrometer (EDS) were used to characterize the physical/chemical properties of the catalysts. These properties could be tailored by altering the PSS concentration (2, 10 and 30 g/L). The CaO-based catalysts synthesized with the incorporation of PSS exhibited an enhanced catalytic activity in the transesterification of palm oil when compared to the CaO catalyst without the assistance of PSS (0-CaO catalyst). The enhanced activity was mainly due to the enlarged pore size/volume and increased active site density of the PSS catalyst. A maximum yield of biodiesel, at 97.2% (89.5% for the 0-CaO catalyst), was reached when the PSS concentration was fixed at 10 g/L. Moreover, this 10-CaO catalyst exhibited excellent reusability, having superior catalytic activity than the commercial CaO (C–CaO) catalyst after being recycled 10 times.