Lipase (triacylglycerol ester hydrolase, EC 3.1.1.3) from Rhizopus arrhizus was immobilized in this work by adsorption on microporous polypropylene and employed for the lipolysis of palm kernel olein. The optimum operating temperature for the lipolysis reaction was determined. The reaction follows Michaelis-Menten kinetics with product competitive inhibition for substrate concentrations in the range of 0.175-0.877M. The apparent K-M and V-max were 0.42M and 691 U/mg protein, respectively. A dissociation constant of the enzyme-product complex, K-I = 29.73 mM, for the product inhibition was also determined. Additionally, the time-courses of the reaction for various substrate concentrations were obtained and correlated sufficiently with those predicted from the theoretical rate equation for a period of up to 2 h. Experimental results indicated that discrepancies between the observed results and the predicted ones increase with reaction time.