Proximate composition and physicochemical analyses were carried out on the seed, pulp and extracted oil of sour sop (Annona muricata). The results showed that the seed contained 8.5% moisture, 2.4% crude protein, 13.6% ash, 8.0% crude fiber, 20.5% fat and 47.0% carbohydrate. The seed also contained 0.2% water soluble ash, 0.79% titratable acidity and 17.0 mg calcium/100 g. The pulp was found to contain 81% moisture, 3.43% titratable acidity and 24.5% non-reducing sugar. Selected physicochemical characteristics included refractive indices of 1.335 for the seed and 1.356 for the pulp, specific gravities of 1.250 for the seed and 1.023 for the pulp, pH values of 8.34 for the seed and 4.56 for the pulp, and soluble solids contents of 1.5 degrees Brix for the seed and 15 degrees Brix for the pulp. The extracted oil (20.5% yield) had a 60.43% unsaponifiable value, 23.54 KOH/g acid value, 100.98 KOH/g saponification value, 1.1 KOH/g peroxide value, 1.464 refractive index, 5.77 pH, 69.5 degrees Brix sosluble solids and 0.2900 specific gravity.