African oil bean seed is an under-utilized leguminous crop planted mainly as shade tree and condiment. The seed contains considerable amount of oil which if extracted will serve as alternative vegetable oil and also boost the economic status of the crop. The main objective of this study was to study the effect of operating parameters on the mechanical oil expression. Operating parameters considered include heating temperature (50, 70, 90, 110 and 1300C), heating time (5, 10, 15, 20 and 25 minutes) and moisture content (8, 10 and 12 % dry basis).A total of 75 experiments were carried out and the maximum oil yield expressed from 500g of seed was 52.3% which translates to an expression efficiency of 86.8% (achieved at seed moisture content 10%db, 15 min heating duration and 900C heating temperature), minimum oil yield for the same quantity of seed was 25.6% (42.4% expression efficiency, achieved at 500C heating temperature, 12% moisture content dry basis and 5 minutes heating time) while the mean oil yield was 36.2% (59.9% expression efficiency of the raw material, at 1300C heating temperature, 20 minutes heating time and 12% moisture content dry basis). It was discovered that operating parameters had significant effect on the yield oil. Regression model was developed to predict the oil yield at known operating parameters.