Hydrogen production from biomass is a green, clean, and zero emissions technology that has attracted increasing attention. This technology has been considered to possess a long-term growth potential, and it is expected to gradually reduce environmental pollution and over-exploitation of resources. In this context, we holistically review this technology and focused on the conversion of biomass into hydrogen using chemical methods (i.e., those with potential for obtaining H-2-rich producer gas streams). Several reaction parameters were discussed and classified herein including biomass conversion methods and conditions, hydrogen production and carbon conversion ratios, the effect of different catalysts types, the catalytic properties of these materials, and their related mechanisms. The overall findings provide new insights for the selection of highly effective and suitable hydrogen production catalysts by biomass conversion applications. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.