AbstractThe “complex” method of M. J. Box has been adapted and used to optimize the design of continuous chemical processes. Such a design involves the extremization of a nonlinear objective function subject of nonlinear equality and inequality constraints. The method consists of finding an original feasible “complex” of solutions, eliminating the worst of these by reflection through the controid of those remaining, and repeating until an optimum has been reached. An example of significant complexity has been solved and the results are reported. The method looks quite promising for use in the optimization of chemical process