In the present study, the ash from discarded Karanja seed shell (KSS), obtained after burning dried seed shells has been identified as one of the most cost-effective and efficient green heterogeneous catalysts for biodiesel pro-duction. Soybean oil methanolsis was used to study the catalytic activity of karanja seed shell ash as solid base heterogeneous catalysts in the biodiesel production. To characterize the catalyst, XRD, WD-XRF, SEM, FT-IR, BET and TGA techniques were utilized. Soybean oil methyl ester was converted under the following experimental conditions, as determined by GC-MS, and FT-IR: a catalyst amount of 2 wt%, a methanol to oil molar ratio of 10:1, a reaction temperature of 65 degrees C, a reaction time of 60 min. The synthesized heterogeneous catalyst is an efficient alternative that may be utilized as an eco-friendly catalyst because it is benign, reusable, sustainable, and widely available.