Biodiesel is a renewable and sustainable energy sources with a great potential to replacernconventional fuel and causes too much less environmental impact. Vegetable oils which can bernedible or nonedible and animal fats can be used as feed stock for biodiesel production. Now a day,rnnonedible vegetable oils are getting more attraction and castor seed oil is among the nonediblernoils having a great potential for biodiesel production. Catalyzed transesterification is mostrnfrequently used method for biodiesel production. The catalyst can be homogenous bas or acidrnheterogenous base or acid and biocatalysts. This research was aimed at producing biodiesel fromrncastor seed oil via transesterification with methanol/ethanol blends. The oil was extracted inrnsoxhlet apparatus using normal hexane as a solvent and its chemical and physical properties wererntested and most of the properties were found to be complying with American society for testing forrnmaterials (ASTM) quality oil. However, its viscosity was found to be too high. The FAM/E-Ern(biodiesel) was produced via transesterification of the castor seed oil with methanol and ethanolrnblends using calcium oxide as solid catalyst. Methanol to ethanol volume ratio, total alcohol to oilrnmolar ratio and catalyst loading were the process variables being studied and Design Expert 7.0.0rnsoftware using central composite design was used to investigate the individual and interactionrneffects of these process variables on the yields of the produced biodiesel. The maximum yield ofrnbiodiesel was obtained at 50:50 methanol to ethanol volume ratio, 9:1 total alcohol to oil molarrnratio and 2.5% catalyst loading. The properties of the produced biodiesel were tested and most ofrnwere found to be complying with that of the ASTM standard biodiesel. However, the density andrnviscosity were found to be above the ASTM standards. Depending on the results obtained from thisrnstudy, it can be concluded that the use of mixed methanol and ethanol for transesterification ofrncator seed oil to biodiesel is viable process. In addition, the use of solid catalyst is a green processrnsince washing of biodiesel with water is not needed and separation of biodiesel from its reactionrnmixture is easy.