High pressure hydrogen storage has become an important transportation channel in areas of new energy development and utilization. Actual hydrogen demonstrations require the exploration of the physical and chemical properties in detail before the practical employment, which is completely different from the ideal gas under high pressure conditions. However, the existing real-gas state equations are not easy to use in calculation of high pressure hydrogen due to its complex behavior, and may lead to an unacceptable error. In this paper, a real-gas state equation of hydrogen in a simplified form is proposed. Compared with the NIST datum, the results obtained from this equation have a maximum error 1.1% and 3.8% respectively within the temperature ranges of 253 K < T < 393 K and 173 K < T < 393 K. Also, the proposed equation exhibits higher precision for the state parameters of hydrogen than existing models. Based on the real-gas state equation of hydrogen, formulas of thermodynamic properties which are necessary for solving the hydraulic and thermal aspects of gas transfer are also proposed. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.