THE OBJECTIVE of the research aim to study biodiesel production from used cooking oil using calcium oxide derived from petroleum scale (PS) as catalyst in transesterification process. Calcium oxide based catalyst was obtained by calcinations of petroleum scale at 850ºC for 4 h. Calcined Petroleum scale catalyst (CPS-CaO) was characterized by different techniques such as: XRD, EDAX, N2-Adsorption /desorption and basic strength by Hammett method. Response surface methodology (RSM) was used for optimizing transesterification process depending on Independent variables, i.e. methanol to oil molar ratio (M:O), catalyst concentration and reaction time. The Optimal parametric values lead to maximum biodiesel yield (~97%) were obtained at Methanol:Oil molar ratio of 12:1; catalyst loading of 2.0 %w/v and reaction time of 2 h at constant temperature 65oC. The results of this study showed a high performance, and the proposed experiment could be used as a new and innovative way to produce biodiesel in the future using cost-effective heterogeneous catalyst based on petroleum scale as a waste materials.