To provide liquid-state alloy material excellent in recycling property with which the generation of hydrogen is obtained and also, a converting efficiency into a valuable material is high and the generated material is already the valuable material and the excellent recycling property is obtained and a byproduct can be generated; and to provide hydrogen using the alloy material and a method for producing the byproduct.

The liquid-state alloy material is composed of gallium-series metal containing at least one selected from tin and silver in the gallium and a composed material having at least one selected from a group composed of metal elements having lower standard electrode potential than that of the gallium and a crystalline hydroxide of the above metallic element on the surface layer of the composition.