Improvement and optimization of a complex chemical plant motivated by energy savings is presented in this paper. The reference object of the research is the sodium tripolyphosphate plant in "IHP-Prahovo", the biggest factory for producing chemical products in Serbia and Montenegro. The research is done by using a step-by-step process integration approach, which combines several computer-based simulation/optimization methodologies. The evaluation of obtained results indicates considerable possibilities for plant efficiency improvement. (c) 2006 Elsevier Ltd. All rights reserved.