This paper presents the results of a theoretical investigation whose aim was the development of a simulation tool for performance prediction of a steam reforming hydrogen production plant, and particularly of its overall energetic efficiency. A 1500 Nm(3)/h hydrogen production plant was simulated. Field data coming from an industrial plant were used for model validation in both design and off design operating conditions. To evaluate the plant performances in terms of energetic efficiency, a particular attention was paid to the simulation of all plant auxiliaries consumptions. Nevertheless the large uncertainty in most of the field data values, the model was able to capture all the relevant phenomena taking place in all the plant components, from reformer reactor up to CO(2) sequestration unit, in the investigated plant capacity range (40-100%). (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.