Abstrak - Biodiesel dapat disintesis dari minyak sawit off-grade menggunakan katalis CaO/serbuk besi pada tahap transesterifikasi. Penggunaan serbuk besi sebagai penyokong katalis CaO memiliki keuntungan yaitu ramah lingkungan dan pemisahan katalis secara magnetik. Penelitian ini bertujuan untuk melihat pengaruh suhu reaksi, rasio mol metanol : minyak dan konsentrasi CaO/Serbuk besi terhadap yield biodiesel. Proses pembuatan biodiesel dilakukan dengan reaksi esterifikasi dan dilanjutkan dengan reaksi transesterifikasi. Data hasil percobaan dianalisis dengan rancangan percobaan (design experiment) metode statistik Central Composite Design (CCD) dan diolah dengan menggunakan program Design Expert 7.0. Perolehan biodiesel tertinggi didapat sebanyak 68% pada suhu reaksi 60 oC, rasio metanol : minyak 6 : 1 dan konsentrasi katalis CaO/serbuk besi 3%-b. Karakteristik biodiesel berupa densitas, viskositas kinematik, angka asam dan titik nyala telah sesuai dengan standar biodiesel Indonesia. Kondisi proses yang paling memberikan pengaruh nyata terhadap yield biodiesel adalah konsentrasi katalis. Kata kunci : biodiesel, CaO, sawit off-grade, serbuk besi, transesterifikasi. Abstract - Biodiesel is one of renewable energy that formed as liquid fuel and has same property with petrodiesel. Biodiesel is able to besynthesized from off-grade palm oil using CaO/Wasted iron as catalyst in transesterification process. Employing Wasted iron as support in CaO has a good impact due to environmentally friendly and magnetic separation of the catalyst. Biodiesel production in this study aims is to see the influence of reaction temperature, molar ratio of methanol and oil and concentration of CaO/Wasted iron towards biodiesel yield. The process was conducted through reaction of esterification and followed by transesterification reaction. Processing of the data in this study was conducted by response surface methodology (RSM) using Design Expert 7.0 program which is experimental design determined by central composite design (CCD) which consists of three variables. The highest result of biodiesel yield was 68% at 60 oC reaction temperature, molar ratio of methanol : oil is 6 : 1 and catalyst concentration of CaO/Wasted iron 3%-w. Biodiesel characteristics like as density, kinematic viscosity, acid value and flash point has been appropriate by Indonesian biodiesel standard. The most significant process condition affecting the yield of biodiesel was catalyst concentration. Keywords : biodiesel, CaO, off grade palm oil, wastes iron, transesterification