Kinetic and mechanistic studies of saponification of seven structurally related and industrially important diesters have been investigated. These saponification processes were followed as series first order reactions and a novel mathematical approach of determinantal method of evaluation of concentrations of half-ester and other end-products was applied. Time ration method and Swain's-standard data for series first order reactions have been utilized for the evaluation of rate data and thermodynamic parameters viz. DeltaE(not equal), -DeltaH(not equal), DeltaG(not equal), DeltaS(not equal) and logA for both the steps which involve the competitive and consecutive saponification reactions. Further, these reactions indicate that the first step of saponification process is much faster than the second step and the laurates are more saponifiable than stearates and oleostearates. The concentrations of half-ester and end-products could not be monitored experimentally, however, they are evaluated through the application of the above said mathematical approach. The advantage of this novel mathematical approach is that the concentrations of half-ester and end-products thus evaluated are with in the mathematical accuracy of +/-0.005%.