Compressive stress, feeding rate and rotational speed are some of the operational parameters that influence efficiency of ail oil expeller. A 3 x 3 factorial experimental design was employed to determine the effects of these parameters on palm kernel oil expression using oil expeller. Obtained data were analysed statistically by regression and ANOVA to obtain relationship between independent variables; compressive stress, feeding rate and speed of operation of the oil expeller and dependent variable; oil yield. maximum oil yield of 46.3% was recorded at 30 MPa compressive stress, 150 kg/h feed rate and 110 rpm of rotational speed while minimum oil yield of 16.3% was obtained at 10 MPa compressive stress, 50 kg/h feed rate and 110 rpm of rotational speed. The developed model equation fitted well with obtained data (R(2) = 0.84) ail indication that the model fits well with the data. The results also showed that predictor correlated positively and directly proportional to the oil yield. However, from the coefficient table, it was discovered that only the compressive stress significantly affect the oil yield at p < 0.05. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.