Biofuels, particularly biodiesel, offer renewable, biodegradable and sustainable alternatives to fossil fuels, alleviating ecological problem such as greenhouse gas emissions from petroleum dependence. This study produced biodiesel from avocado seed oil (ASO) which is an underutilised non-edible waste- and evaluated its blends with petroleum diesel. Seeds were washed, sun dried, ground and extracted using a Soxhlet instrument with n-hexane, yielding 12.50 % oil. ASO exhibited an acid value of 3.02 mg KOH/ g, free fatty acid content of 1.55 %, specific gravity of 0.90, kinematic viscosity of 6.20 mm²/s and pH of 6.90. It was observed that fatty acid profiling revealed oleic acid (66%) as dominant, followed by palmitic acid (13.05%). Base-catalysed transesterification (6:1 methanol-to-oil molar ratio, NaOH catalyst) yielded 92 % B100 biodiesel. Its characteristics include an acid value of 1.61 mg KOH/g, kinematic viscosity of 8.70 mm²/s, specific gravity of 0.90, flash point of 120 °C, cloud point of 2 °C, and cetane number of 51. Blends B10(10:90 v/v; i.e., biodiesel: diesel) and B20 (20:80 v/v) showed acid values of 0.96 and 1.02 mg KOH/g, viscosities of 4.80 and 5.90 mm²/s, specific gravities of 0.85 and 0.89, flash points of 105 and 110 °C, cloud points of 1 and -1 °C and cetane numbers of 52 and 50, respectively. Most properties met ASTM D6751 and EN14214 standards, except B100 viscosity (slightly elevated). These results affirm ASO-based biodiesel and blends as viable petroleum diesel substitutes, advancing waste valorisation for sustainable energy.
