The ZnO/Zn based CH4 reforming (MR) and H2O splitting (WS) process was thermodynamically scrutinized in this investigation. Two process arrangements i.e., ZnO/Zn based open (ZS) process and ZnO/Zn based semi-open (ZSH) process were considered to perform the thermodynamic analysis. The ZS process resulted into production of Zn and syngas, whereas the H-2 and syngas was generated from the ZSH process. For both processes, the results obtained during the equilibrium analysis shows that the thermal reduction (TR) of ZnO was feasible at 1200 K in presence of CH4 as the reducing agent. In case of the ZS process, the rise in the CH(4)p/ZnO ratio from 0.1 to 1 resulted into an upsurge in the total solar energy required to run the cycle, solar zs) and solar-to-fuel energy conversion efficiency (713 iar-w-fuet-zs) by 460.1 kW and 13.0%, respectively. For the ZSH process, the total solar energy required to run the cycle (O.- was decreased from 598.3 to 595.9 kW and the solar-to-fuel energy conversion efficiency 77(,,solar to fuel ZSH) was increased from 76.6 to 76.7% with the upturn in the WS temperature (Ti) from 500 to 675 K. At identical experimental conditions, the nsolar to fuel ZSH was observed to be higher than the nsolar to fuel ZS" (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.