T HE 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 /d...