Monoacylglycerol emulsifiers commonly employed in the food, cosmetic and pharmaceutical industries can be produced by a glycerolysis reaction using lipase. The concentrations of two substrates (palm olein and glycerol) in the glycerolysis reaction were strictly interdependent. Therefore, it was impossible to perform a classic kinetic study by fixing the concentration of one substrate and changing the concentration of the other substrate. Here, a mathematical model approach is a useful tool to independently assess the effects of hypothetical changes in the concentrations of each. In essence, this analysis permits one to examine various aspects associated with the dynamics and equilibrium of the glycerolysis reaction that cannot be investigated experimentally. In this study a mathematical model, taking into account the mechanism of the glycerolysis reaction for monoacylglycerol production using immobilized lipase, has been developed. From the proposed model, the effects of varying the initial concentrations of substrates on the initial production rate and yield of monoacylglycerol were simulated. The most significant finding from simulation was that an increase in the initial concentration of triacylglycerol leads to an increase in the initial production rate of monoacylglycerol, but there is a limit beyond which increasing the initial concentration of triacylglycerol results in a low yield of monoacylglycerol. The simulation results show that mostly glycerol reacts with fatty acid of triacylglycerol to produce monoacylglycerol in a glycerolysis reaction. From a thermodynamic standpoint, a greater incorporation of glycerol is expected because a higher concentration of this acyl acceptor should shift the equilibrium towards a greater glycerolysis reaction.