The abundant rice production in Indonesia produces about 20% of rice husks. Rice husk is still not used properly so that it only becomes a pile of agricultural waste, rice husk ash contains a compound that can be used as a catalyst support, namely Sio2. Also waste cooking oil from fried getuk in the area of Sokaraja Banyumas which produces 1000 liters of used cooking oil per day. This study aims to determine the effect of adding support for rice husk ash catalyst that has been calcined with KOH impregnation as a catalyst for making biodiesel from getuk fried cooking oil. Rice husks were calcined at 500oC for 3 hours and then impregnated with 2N KOH. Esterification was carried out to reduce the FFA value in used cooking oil. Transesterification was carried out on the esterification results with the mass weight of the catalyst (10; 12.5; 15; 17.5; 20 grams). The results obtained the best biodiesel was obtained in the 17.5 catalyst experiment with a temperature of 55oC. with a yield value of 95.47, a density of 878 kg/m3, a viscosity of 4.799 Cst.