EMSO simulator is an equation-oriented process simulator with a graphical interface for modeling complex dynamic or steady-state processes. It is CAPE-OPEN compliant. EMSO stands for Environment for Modeling, Simulation, and Optimization.^[1] The ALSOC Project - a Portuguese acronym for Free Environment for Simulation, Optimization and Control of Processes -, which is based at the UFRGS, develops, maintains and distributes this object-oriented software. Pre-built models are available in the EMSO Modeling Library (EML).^[2] New models can be written in the EMSO modeling language or a user can embed models coded in C, C++ or Fortran into the simulation environment.