Fatty Acid Methyl Esters (FAMEs) from transesterification of Jatropha oil were obtained by both acid and base catalyzed transesterification reactions. These FAMEs were epoxidized in or without solvent by either peroxyformic acid or peroxyacetic acid, formed in situ by 30 hydrogen peroxide. n-hexane was used as solvent. Detailed study regarding effects of type and concentration of organic acid used in and without solvent at temperatures 50°C, 60°C and 69°C is presented here. Molar ratio of FAMEs: H 2O 2 was fixed at 1:3.5 and reaction time was fixed at 6 hours. The formic acid-FAMEs molar ratio was (FAMEs: Formic acid) 1:0.45, while for acetic acid molar ratio was (FAMEs: Acetic acid) 1:0.60. For formic acid, it was found that without solvent, the conversion was 79 while in solvent; it was found that the highest conversion (83) was obtained at a temperature of 60°C. When acetic acid as oxygen carrier was used, it required 1.5 H 2SO 4 as catalyst for the reaction in solvent to give maximum conversion of 71. Without solvent the conversion was 74 at 69°C. The products were analyzed by NMR, GC-MS, FT-IR and volumetric analyses for qualitative and quantitative determinations. © 2011 IEEE.