A model for the enzyme kinetics of lipolysis was developed where the rate limiting step of the reaction is the interfacial binding step. Binding involves the association of the enzyme with a cluster of substrate molecules and a conformational change in the enzyme, resulting in an interfacially penetrated lipase bound to a cluster of substrate molecules. The resulting derived rate equation is identical to the HIll equation. Fits of the model to experimental velocity vs. substrate concentration data from the literature allowed for the determination of enzyme-substrate interface dissociation constants and reaction order with respect to substrate concentration.