This paper reports the thermodynamic analysis of the solar methanothermal reduction of Sm2O3 for the co-production of Sm and syngas in (a) Sm-Syngas open cycle, and (b) Sm-Syngas closed cycle. As per the chemical thermodynamic equilibrium modeling, the conversion of Sm2O3 into Sm increase with the increase in the CH4/Sm2O3 ratio and 100% conversion is possible at 2528 K if CH4/Sm2O3 ratio is equal to 3 is used. Exergy efficiency analysis of both open and closed cycles indicate that the Q(Sm2O3-reduction), Q(solar), Q(re-radiation), and Q(quench) increases with the increase in the CH4/Sm2O3 ratio. Likewise, WFC-Ideal-1, Q(FC-Ideal-1), and HHVsyngas-1 also increases with the upsurge in the CH4/Sm2O3 ratio. Similar observations were realized in case of Sm-Syngas closed cycle. The eta(exergy) (33.91%) and eta(solar-to-fuel) (45.93%) of the Sm-Syngas open cycle was observed to be maximum in case of CH4/Sm2O3 ratio = 3. As one of the applications, Sm was utilized toward splitting of H2O and CO2 together for the production of syngas via Sm-Syngas an closed cycle. At similar operating conditions, the eta(exergy-closed) (45.22%) and eta(solar-to-fuel-closed) (61.24%) of the Sm-Syngas closed cycle was observed to be higher as compared to the Sm-Syngas open cycle. Furthermore, it was observed that, these efficiency values can be increased significantly due to the utilization of higher values of C and recycling of the heat rejected by the quench unit and H2O/CO2 splitting reactor. (C) 2016 Elsevier Ltd. All rights reserved.