Hydrogen energy can help in solving the problem of greenhouse gas emissions which results in reduced global warming and stress on the fossil fuel supply and price, provided that hydrogen is produced by clean processes involving renewable energy. Solar hydrogen production via two-step thermochemical cycle is an appealing technique. This article attempts to present a review with aspect to solar thermochemical hydrogen production redox pairs, reactor design technology, general assessment, etc. Some novel reactors have been designed for different redox pairs in recent decade years. We give a comparison between different hydrogen technologies and summarize the problems that exist in the cycle. Though solar thermochemical hydrogen production technique is a promising and potential roacute to solve energy crisis problem, it still has many problems that need to be solved in the future.