This paper investigates the effects of flow rate of gasification oxidant, gasification agent and coal type on the energy efficiency and hydrogen production rate of a proposed system. The present system consists of a pressurized entrained flow gasifier integrated with a cryogenic air separation unit, a water gas shift membrane reactor and a combined cycle. Aspen Plus software is used to develop and simulate the integrated system. Three different types of coal are fed to the gasifier. A Gibbs free energy based model of the gasification process is developed and validated. The Gibbs free energy based model is then used to assess the effect of gasification parameters since it is more straightforward regarding changing input flow rates. It is found that gasifying low grade coal is preferable in terms of energy efficiency to gasifying high grade coals, which are more advantageous for combustion regarding energy efficiency. (C) 2016 Elsevier Ltd. All rights reserved.