Many chemical processes need large computation time to simulate. It has been observed that the speed of a process simulation depends to a large extent on evaluation of certain important functions in the system to be simulated. One such function is K-value estimation function which involves heavy vapor-liquid equilibrium calculations. Because of large number of K-value calculations, there can be a bottleneck in simulation convergence. Thus within process simulation applications computational speed is often emphasized and accuracy is compromised. In situ adaptive tabulation or ISAT, a storage and retrieval technique is proposed for speeding up K-value estimation in a process simulator (CHEMCAD®) using the input-output data. C language code is developed to implement ISAT algorithm for this application. The C code is then converted into Dynamic link library to be able to be used vii by main CHEMCAD® code as required. The overall testing with different K-value databases gave promising results improving computational time while maintaining accuracy. / text