This chapter provides an overview on solid-state hydrogen materials, specifically on absorption-based materials, including metal hydrides, complex hydrides, chemical hydrides, and emerging materials like high-entropy alloys. The broad classification of each class of materials has been outlined by examining their key features---crystal structures, electronic structure, reaction mechanisms, kinetics, and thermodynamic characteristics for hydrogen storage. The advantages and limitations, along with the methods to improve their desired characteristics, are discussed in relation to practical end use. The chapter concludes with a brief techno-economic comparison of major hydrogen storage methods, such as underground, compressed, and liquid and metal hydride-based hydrogen storage methods, paving a pathway for choosing appropriate storage technology based on the applications and quantity of hydrogen to be stored.