Solar energy provides abundant renewable energy resources that can be utilized for power, high-temperature heat, and fuel generation. To tackle the intermittency issue of solar energy, fuel generation provides a high energy density storage solution that can also act as a feedstock for chemical production. Solar fuels can be generated directly using thermal energy (e.g. solar thermochemical processes), photo pathways (e.g., photoelectrochemistry), or a hybrid of both. The solar thermochemical processes utilize concentrated solar thermal energy as the high-temperature heat input. These processes could achieve high conversion efficiency due to the potential of full solar spectrum utilization and produce primary fuels such as hydrogen, and synthetic gas (with \({\text{CO}}\) and \({\text{H}}_{2}\) as main components) or derived fuels such as methanol, and synthetic liquid fuels from \({\text{H}}_{2} {\text{O}}\) and \({\text{CO}}_{2}\) . This chapter describes various thermochemical pathways that can be used for fuel generation. Among these, a metal oxide-based redox looping thermochemical cycle for \({\text{H}}_{2} {\text{O}}\) and \({\text{CO}}_{2}\) splitting is the most viable option due to its direct use of solar energy, process simplicity, and scalability. It is a two-step process in which a metal oxide is first reduced at high-temperature and low pressure, releasing oxygen and forming a lower valance metal oxide. In the second step, the reduced metal oxide reacts with steam/ \({\text{CO}}_{2}\) and generates \({\text{H}}_{2}\) / \({\text{CO}}\) . The metal oxide then re-oxidizes back to its original state, making it a closed-loop process. The current Technology Readiness Level of this process remains low due to several technical challenges at the material, reactor, and system levels. From the material perspective, a cheaper material with faster reaction kinetics and good cycle stability is needed. Challenges at the reactor level include reactor material limitation and sealing issues due to high operating temperature, energy penalty for low-pressure creation, and heat transfer in the porous material. Since the metal oxide reduction and water-splitting steps occur at different temperatures, effective heat recuperation between these two steps is crucial to achieve higher process efficiencies. However, this is extremely difficult due to severe operating conditions. The chapter explains the thermodynamics of the thermochemical cycles, reactive material requirements, reactor development, and system-level analysis. The opportunities and challenges of these processes are described, and a future outlook of the technology is provided.