A method for environmental performance assessment is presented in this paper. The proposed method considers the procedure for environmental performance comparison of design alternatives as a multi-criteria decision-making (MCDM) problem. Integrated assessment model based on analytic hierarchy process (AHP) is presented for solving MCDM problem. An integrated environmental index (IEI) for chemical processes is proposed to combine resource conservation, energy consumption and potential environmental impacts associated with releases. This paper presents IEI as an environmental performance comparison index. As a case study, two alternatives of ethanol production are assessed by means of the proposed method.