Recent studies show that thermochemical cycles has a great potential for green hydrogen generation. In this study, the thermodynamic performance assessment of a solar based Sulfur-Iodine (S-I) thermochemical cycle for hydrogen generation is performed focusing on the energy and exergy methods. Moreover, we investigated that various reference environment and reaction temperatures effects on energy and exergy efficiencies of S-I cycle steps. The results of thermodynamic analyses indicated that energy and exergy efficiency of S-I cycle are found to be 43.85% and 62.39%, respectively. In addition, the overall energy and exergy efficiencies of cycle are computed as, 32.76% and 34.56%, respectively. It was concluded that the S-I thermochemical cycle offers a feasible and a diverse option for hydrogen generation and seems to be a promising cycle. (C) 2017 Elsevier Ltd. All rights reserved.