The aim of this project was to develop and implement an optimisation methodology that combines process thermo-modelling and process integration in a thermo-economic optimisation framework for fuel cells systems. During this project, a generic software has been developed to perform optimisation of integated energy systems. OSMOSE stands for “OptimiSation MultiObjectif de Systemes Energétiques intégrés” (MultiObjective Optimisation of Integrated Energy Systems). The developed approach and software have been used to optimise a hybrid PEM and gas turbine system. This report contains the project description, the methodology the obtained results, the full PEM process flow diagram, examples of results and the manual of OSMOSE.