Hydrogen has emerged as a promising energy carrier, offering a viable solution to meet our current global energy demands. Solar energy is recognised as a primary source of renewable power, capable of producing hydrogen using solar cells. The pursuit of efficient, durable, and cost-effective photocatalysts is essential for the advancement of solar-driven hydrogen generation. Copper slag, a by-product of copper smelting and refining processes, primarily consists of metal oxides such as hematite, silica, and alumina. This composition makes it an attractive secondary resource for use as a photocatalyst, thereby diverting copper slag from landfills and generating 0.113 mu mol/g h of hydrogen, as noted by Montoya. This review aims to thoroughly examine copper slag as a photocatalytic material, exploring its chemical, physical, photocatalytic, and electrochemical properties. Additionally, it evaluates its suitability for water treatment and its potential as an emerging material for large-scale solar hydrogen production. C1 [Leiva-Guajardo, Susana I.; Fuentealba, Edward; Portillo, Carlos; Madrid, Felipe M. Galleguillos] Univ Antofagasta, Ctr Desarrollo Energet Antofagasta, Antofagasta 1240000, Chile. [Toro, Norman] Univ Arturo Prat, Fac Ingn & Arquitectura, Iquique 1100000, Chile. [Morel, Mauricio J.] Univ Atacama, Dept Quim & Biol, Ave Copayapu 485, Copiapo 1530000, Chile. [Soliz, Alvaro] Univ Atacama, Dept Ingn Met, Ave Copayapu 485, Copiapo 1530000, Chile. C3 Universidad de Antofagasta; Universidad Arturo Prat; Universidad de Atacama; Universidad de Atacama