This study focuses on the preparation and characterization K2O-CaO/γ-Al2O3, K2O doped CaO which is supported with γ-Al2O3, and their catalytic activity in the transesterification of waste cooking palm oil with methanol to produce biodiesel. The catalyst was prepared by wet impregnation followed by activation at 700oC for 4:30h in the furnace. The catalyst was characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ICP-OES and Hammett indicator method. The catalyst which was reused for four consecutive cycles exhibited a gradual fall in its catalytic capability due to catalyst leaching. The leaching tendency of the catalyst was analyzed by ICP-OES machine and it is determined that 18% K and 8.5% Ca leached into the reaction media at the end of the fourth cycle. Also, this study consists of the optimization of the biodiesel yield produced via transesterification of waste cooking palm oil using K2O-CaO/γ-Al2O3 solid base catalyst. Response surface methodology (RSM) in combination with central composite design (CCD) was used to optimize the operating parameters. Methanol to oil molar ratio, catalyst loading and reaction temperature were chosen as the variables and the response selected was biodiesel yield. The optimum reaction conditions obtained were methanol to oil molar ratio of 12:1, catalyst loading of 5.6wt% and reaction temperature of 64°C. At these optimal operating conditions biodiesel yield obtained was 97.8% for 3h reaction. Biodiesel was chemically characterized with 13C NMR and 1H NMR machine. The yield of biodiesel determined by1H NMR was 96%.