An integrated pathway (heterogeneous catalyst with supercritical pathway) was studied to develop a most viable route for the synthesis of fatty acid methyl esters useful as biodiesel. Madhuca indica (Mahua) oil was transesterified using supercritical methanol and ZnO at 523 K, 10 MPa and molar ratio of 40:1 (alcohol:oil). ZnO was synthesized by solution combustion using various fuels (urea, glycine, lactose, oxalyl dihydrazide, ascorbic acid (AA)). Also, different morphologies of ZnO (nanorods (NR), nanoflowers, nanoparticles, nanospheres) were obtained via hydrothermal, precipitation, sonochemical and sol-gel synthesis. Pseudo first order rate constants ranging from (3.46 to 16.7) × 10−4 s−1 (>0.99 × 10−4 s−1 for uncatalyzed reaction) at 523 K, 10 MPa were obtained. ZnO-AA (solution combustion) and ZnO-NR (hydrothermal) were found to be the most active catalysts. Activation energies of 42 kJ/mol and 17 kJ/mol (<75 kJ/mol for uncatalyzed reaction) were obtained with ZnO-AA and ZnO-NR indicating the superiority of the integrated process. © 2019 Elsevier Ltd