A straightforward method for calculating physical and chemical exergies of material stream has been proposed. Furthermore, proposed procedure for exergy calculation has been implemented in one of the most widely-used flowsheeting simulators, namely HYSYS by utilizing fifteen main user variables for material streams. Visual Basic codes required for each of the mentioned user variables have been also presented within the text. Such computer-aided exergy calculations will make exergy analysis more accessible in HYSYS process simulator resulting in more insight into the nature of irreversibilities associated with specific process. (C) 2011 Elsevier Ltd. All rights reserved.