This paper focuses on a comparative study of five renewable energy based hydrogen production systems. These five systems considered in this regard are (a) Cu-Cl integrated with Kalina cycle (system 1), (b) hybrid sulfur (HyS) cycle integrated with isobutane cycle (system 2), (c) quintuple flash power plant integrated with electrolyzer (system 3), (d) heliostat field integrated with steam cycle, Organic Rankine Cycle (ORC) and electrolyzer (system 4), and (d) solar photo-voltaic/thermal (PV/T) integrated with triple effect absorption cooling system and electrolyzer (system 5). The results obtained here show that energy efficiencies of these five systems are not affected by the rise in ambient temperature. It is also found that among these five systems studied, system I performs the best and system 5 ends with the worst. The energy and exergy efficiencies, sustainability index, and energy required to produce unit L/s of hydrogen for system 1 are found to be 59%, 83%, 5.9, and 16.58 kW, respectively. (C) 2013 Elsevier Ltd. All rights reserved.