<p>The present research addresses key barriers in converting high-FFA, non-edible oils like neem into biodiesel, mainly low yields and process inefficiency using conventional catalysts and heating methods. Study reports a novel approach utilizing a graphene oxide based heterogeneous catalyst (KOH@GO), synthesised by a modified Hummer’s method, for the production of biodiesel from non-edible neem oil. For efficient transesterification, initially, the high free fatty acid (FFA) content of neem oil was reduced via esterification to lower its acid value. Subsequently, a microwave- assisted transesterification was adopted to enhance reaction kinetics and energy efficiency. Significant reaction parameters including methanol-to-oil molar ratio, reaction time, catalyst loading, and temperature, were systematically optimized to study their effects on production efficiency. This innovation enables efficient, high-yield biodiesel production while enhancing catalyst reusability and reducing energy input, thus offering a scalable and sustainable alternative for biodiesel production from challenging feedstocks.</p> Graphical Abstract <p></p>