Biodiesel is an alternative fuel derived from plant oil, animal fat or used oil through esterification with alcohol where it can be used without modifying the engine of a diesel machine. Used cooking oil is categorized as a waste that pollutes the environment, which can be the cause of some diseases such as cancer, coronary heart disease, stroke, and also hypertention. Calcium oxide (CaO) is an alkali metal oxide that can be used as a heterogeneous catalyst in biodiesel synthesis, its raw materials can be sourced from waste material such as chicken bones. The conversion of calcium to CaO is conducted through thermal decomposition of calcium carbonate (CaCO3) from chicken bones heated at a high temperature. This study utilizes used cooking oil as the raw material and CaO as the catalyst. The purpose of this study was to determine the effect of the amount of catalyst in the biodiesel synthesis from used cooking oil and also the effect of temperature variation on chicken bone heating as the material of the catalyst. This study was carried out by transesterification and calcination procedures with temperature variations of 700, 750, 800, 850 and 900oC, as well as the variations in the amount of CaO as the catalyst of 2, 3, 4, 5, and 6 % wt. This study shows that the most favorable calcination temperature for the chicken bones is at 750oC and the percentage of CaO as the catalyst is 2%.