Invensys SimSci-Esscor PROII v9.4 SimSci PRO/II PRO/II optimizes plant performance by improving process design and operational analysis and performing engineering studies. Designed to perform rigorous heat and material balance calculations for a wide range of chemical processes, PRO/II offers a wide variety of thermodynamic models to virtually every industry. PRO/II is cost effective, thereby decreasing both capital and operating costs.