The thermodynamic efficiency analysis of the MgO/Mg based CH4 reforming and H2O splitting process is performed in this paper. The study is conducted by considering two process configurations, namely, a) MgO/Mg based open process where Mg and syngas is produced (MS process), and b) MgO/Mg based semi-open process where syngas and H-2 is generated (MSH process). The thermodynamic equilibrium analysis indicate that the best possible thermal reduction temperature for both processes is 2100 K and, in case of the MSH process, the water splitting step is feasible in the range of 500-900 K. As per the findings, for the MS process, the solar energy required to drive the process increases by 958.2 kW as the CH4/MgO ratio upsurges from 0.1 to 1. For the MSH process, the minimum amount of solar energy needed to run the process i.e., 1203.1 kW can be accomplished at water splitting temperature of 900 K and CH4/MgO molar ratio = 1. Based on the solar-to-fuel energy conversion efficiency, the MSH process appears to be more advantageous (54.5%) than the MS process (41.3%). The solar-to-fuel energy conversion efficiency of the MSH process can be further enhanced up to 65.6% by reclaiming 50% of the heat dissipated by the coolers and WS reactor. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.