BackgroundThe impact of Fe doped TiO2 nanocatalyst on the heterogeneous catalytic transesterification reaction of coconut oil into biodiesel has been investigated. MethodsThe nanocatalyst was prepared by sol-gel method using titanium isopropoxide as TiO2 precursor and Fe(NO3)3 as iron (Fe) source. Several conditions of Fe-TiO2 were synthesized, each with Fe concentration of 0.5 %, 1 %, and 1.5 %, and calcined at 500 °C. The nanocatalyst's physical and chemical characteristics including phase crystallinity and morphology were examined. Significant findingsWe found that the biodiesel conversion efficiency increases with the increasing of Fe content in the Fe-TiO2 nanocatalyst and optimum at the Fe concentration of 1.5 % (w/w). The optimal Fe-TiO2 nanocatalyst could yield biodiesel output as high as 30.8 %, under at a relatively low temperature of 60 °C. Furthermore, the presence of the nanocatalyst effectively reduced the free fatty acid content in the biodiesel product by 1.43 %. Moreover, the acidity of the produced biodiesel was exceptionally low, at 0.02 %, primarily attributed to lauric acid. These exceptional performances are believed to be attributed to the enhanced surface chemistry properties of the Fe-TiO2 nanocatalyst. The Fe-TiO2 system is expected to find extensive application in the cost-effective production of biodiesel.