The objective of this paper was to optimize the viscosity of transesterified Jatropha Curcas biodiesel has gained importance for boosting the fuel industry and improving the production efficiency of biodiesel. A mathematical model for the transesterification of Jatropha Curcas oil was developed at five different process parameters, such as catalyst concentration, reaction time, methanol to oil ratio, stirrer speed and extraction temperature. A three -level -five factorial Box -Behnken was employed to design the experiment. Analysis of variance (ANOVA) of experimental results at 95% confidence level showed that catalyst concentration and reaction time were significant process parameters. The models can be successfully adopted in fuel industry to minimize the viscosity of transesterified Jatropha oil. The prepared Jatropha Curcas biodiesel (JCB) conformed to the ASTM and IS standards specifications.