An exergo-economic optimization methodology for complex multicomponent-multiproduct systems based on the isolated optimization of subsystems or components is presented. The selection of subsystems or components to be optimized is dictated by two parameters: the exergetic efficiency (epsilon) and the elasticity (pi(i)), the latter measuring the variation of the global system efficiency with the efficiency change of the ith subsystem i(partial derivative epsilon(gl)/partial derivative epsilon(i)), both evaluated for the given operational conditions. The thermodynamic and economic interactions between components or subsystems are included in the method. An objective cost function consisting of capital and exergy losses costs is defined for optimization purposes.