The operation and performance of a laboratory-scale catalytic bioreactor used for the hydrolysis of mixed natural oils into free fatty acids in the presence of free lipase (triacylglycerol ester hydrolase, EC 3.1.1.3) is described. The novelty of the reactor system is the intensification of the reaction kinetics by electrostatic spraying of the lipase as a dispersion of very fine droplets into the oil phase. The effect of phase ratio and held strength on the kinetics were measured for a simple batch type spray reactor. Coalescence rates within the electrostatic spray reactor were shown to be significantly higher than conventional stirred systems. The kinetic data were compared with a control experiment in which the free lipase suspension and oil were contacted by mechanical mixing in the absence of any externally applied electrical field.