In this work, a green solid acid catalyst derived from the waste material of the angel wing shell (AWS) was synthesized using a two-step method: calcination followed by sulfonation. The calcined angel wing shell (CAWS) was supported with varied concentrations of sulphuric acid to obtain an optimum high acidity level of the catalyst. The CaO-based calcined angel wing shell sulphated (CAWS-(x)SO4) catalysts, where x = sulphuric acid concentration, were analysed using X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, temperature programmed desorption of carbon dioxide and ammonia, BET surface area, and scanning electron microscope. The specific surface area, pore volume, and pore diameter of the CAWS was increased significantly after being sulphated at the optimum sulphuric acid concentration: whereas, the CAWS-((7)) SO4 showed the highest total amount of acidity (4726 mu mol/g). The optimal FAME conversion (98%) from the PFAD was acquired at the reaction temperature of 80 degrees C, 15:1 MeOH:PFAD molar ratio and 5 wt% catalyst loading for a 3 h reaction time. The CAWS-(7)SO4 catalyst was reused two times with a high FAME yield without further treatment under optimized reaction conditions. The use of the AWS for the synthesis of catalysts has enormous potential for biodiesel production from high FFA oils due to its lower production cost, abundant availability and high catalytic activity. (C) 2018 Elsevier Ltd. All rights reserved.