Research results enable consumption of energy, water and raw materials to be reduced and the production to be rationalized. Environmental pollution can be deminished: lower energy usage reduces the production of green house gases and preserves nonrenewable resources of energy, recycling reduces production of waste and usage od nonrenewable raw materials, capacities of purification lines increase their operation improves. Process retrofits improve the competitivness of the Slovenian chemical and related process industries. One of the objectives was development of an integrated methodology for the optimization of process systems at different levels of activity (process and product design and retrofit, planing and scheduling of processes and process operations). We have developed the most advanced mathematical programming techniques and methods (LP, NLP, MILP, MINLP), by which it is possible to find optimal and feasible solutions. It should be noted that process optimization has been regarded as one of those critical technologies that require small investment and yet enable to significantly improve the current efficiency and market competition of the existing small, medium or large scale processes. The developed knowledge has been transferred into practice by applied projects: - rational use of energents in a refinery and petrochemicals production, - regeneration of waste heat and energy integration in thread production, - energy and water use minimization in sugar beet industry, - energy survey in tanine production, - investigation on crystallization kinetics in pharmaceutical industry, - evaluation of a waste mineral oil refinery process in relation to the IPPC directive. The 'spin-off' company of the research group in the regional technological park is working successfully - a National Cleaner Production Center has been established in it, too. A national meeting of about 300 chemists and chemical engineers is organized by the group each year. The group has also taken part in the professional programme accompaniing the plastics, rubber and chemicals fair PLAGKEM.