A method of producing hydrogen and sequestering carbon or sulfur includes generating a fluid including at least one of water, steam, hydrogen sulfide, carbon dioxide and heat as a byproduct of a surface facility and injecting the fluid into a subsurface formation. The subsurface formation can include a porous rock, in various forms of porosity such as intragranular, intergranular, fracture porosity. The method can further include heating the fluid to stimulate an exothermic reaction of the fluid with components of the subsurface rock formation and produce a hydrogen reaction product and one or more of sulfur minerals from the hydrogen sulfide or carbon minerals from the carbon dioxide. The fluid can be heated to between about 25° C. and about 500° C. The method can also include extracting the hydrogen produced from the reaction of the fluid with the subsurface rock formation and mineralizing sulfur or carbon in the porous rock.