Abstract The interest in the use of non-noble metal catalysis is quite relevant to biomass processing due to costs, environmental concerns and the substantial scale of these operations. The aim of this article is to cover all aspects of the use of iron based catalysts in various biomass processing applications, especially focusing on the developments in the last five years. The appeal of metallic iron and its compounds in catalysis as well as the diversity of the type of transformations are discussed in the introduction sections of this review. The recent advances in the use of iron or its compounds in biomass pretreatment, saccharification, liquefaction and pyrolysis are reviewed as major topics in the review article. In addition, the use iron based catalysts in processing biomass derived small molecules to fuel; polymer and chemical feedstocks are also discussed in the article.