Electrochemical deposition, structure, and properties of Fe–W alloys are studied. The alloys formed at a low current density are crystalline supersaturated solid solutions which are magnetic. At higher current densities, amorphous nonmagnetic alloys of the same composition are formed. As a result of treatment at 500–600°С, both amorphous and crystalline transform into a more equilibrium binary system, containing W solid solution in Fe and an intermetallic compound. The concentration of the remaining W in the solid solution was much higher than the equilibrium solubility. A considerable amount of hydrogen incorporates into the deposits. The deposits may be qualified as ternary Fe–W–H alloys. The incorporated hydrogen plays a crucial role in the transition from a crystalline state typical for specimens produced at low current densities to the amorphous or nanocrystalline deposits formed at higher current densities.