The mathematical model of hydrogen network is developed to minimize the total exergy consumption of the hydrogen utility and compressor work. The constraint on the hydrogen to oil ratio of hydrogen consuming reactor is represented by that on pure hydrogen load of each sink. Instead of reducing the hydrogen concentration and pure hydrogen load to the minimum directly, all the possible combinations of them are considered. Furthermore, the optimal flow rate of each sink is taken as a variable in the model and the matching flow rate constraint is introduced to remove the source-sink match with small flow rate. This method can be applied to target the minimum utility consumption of systems with any number of impurities. In addition, both the hydrogen to oil ratio and hydrogen concentration can be guaranteed not be less than their lower limitations. The proposed method is applied to the hydrogen network of a real installation, and the results show the hydrogen utility saving potential accounts for 16.52% of the current hydrogen utility consumption. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.