The work presents a model which solves the heat exchanger network (HEN) synthesis problem using geometric mean temperature difference (GMTD) in place of the logarithmic mean temperature difference (LMTD). With the aid of logarithmic transformation and piecewise linearization, the problem is stated in a linear form and thus global optimality can be assured for the model. The accuracy of the approximation is discussed and the results obtained for three known case problems show that the usage of GMTD instead of LMTD can be justified. The GMTD-based model produces designs that are sufficiently accurate and comparable with the ones obtained using the LMTD. (C) 2007 Elsevier Ltd. All rights reserved.