The world is facing severe energy crisis attributed to global oil reserve depletion, increasing consumption rate, incessant oil price hike and above all environmental concerns (air pollution and emission of Greenhouse Gases) dictate that the world community must hunt for alternative and sustainable energy sources. One of the mitigation efforts considered in response to the crisis is finding substitute for petroleum oil. Biofuels are becoming the most reliable energy sources, among which, biodiesel attracted attention to substitute for the ever-increasing petrodiesel demand and consumptions for every activity of human beings. This research project assessed the potential of biodiesel production from oil seeds in Ethiopia and the qualities were compared to identify the most suitable species. Samples of oil seeds were collected from different locations. Suitable areas were delineated using ArcGIS software and the spatial analyst tool. Soxhlet extraction method was used to extract oils from each species, using solvent, hexane. The biodiesel was synthesized by transesterification process and characterized by determining density, kinematic viscosity, iodine value, saponification number, peroxide value, cetan number, heating value, cloud point, flash point, acid number and distillation test. GC analysis was conducted to determine the fatty acid compositions. The oil content results from the five collections of R. communis ranged from 36.45 to 45.76 %w. B. carinata rendered oil content of 47.62 %w and J. curcas, investigated at three different conditions resulted oil contents ranging from 29.55 to 41.04 %w. The gross heat contents of the biodiesels from B. carinata, J. curcas, R. communis and E. guineensis were found to be 39.31, 38.71, 36.86 and 38.95 MJ/kg respectively. J.curcas conforms with all the standard specifications of ASTM D 6751 and EN 14214, except for its flash point result of 120 o C i.e., less than the EN 14214 specification. R. communis fails to meet both the standards having density (0.9269 g/mL), kinematic viscosity (10.94 mm 2 /s) and flashpoint (95 °c) and that of EN standard due to its acid No. (0.566 mgKOH/g). B. carinata meets both standards, except in acid number result of 0.885 file:///C|/Users/3020/Desktop/enviromental%20science/Thesis%20Mesfin%20Kinfu%202008.pdf.txt[6/1/2018 11:04:45 AM] mgKOH/g, which exceeded both limitations, and kinematec viscosity result of 5.09 mm 2 /s exceeding the range set by EN 14214. E. guineensis fails to meet both the standards in density (0.9121 g/mL), kinematic viscosity (13.91 mm 2 /s) and acid number (1.802 mgKOH/g). It can be concluded that, amongst the oil plants investigated, J. curcas surpassed in every aspect, that rendered it the most suitable and potential candidate as a substitute for diesel, seconding B. carinata, while R. communis and E. guineensis can be used up to 20% blends with the other two. Moreover, the physicochemical characteristics were improved by blending the biodiesels from different oils, and promisingly agreed with the standard specifications. Key words: Transesterification, Biodiesel, alternative feedstock, area suitability, physicochemical properties, blends.