An anhydrous electrolyte for a magnesium battery. The anhydrous electrolyte includes a magnesium salt having the formula Mg(BH4)2. The electrolyte also includes a solvent, the magnesium salt dissociating in the solvent. Various solvents including aprotic solvents and molten salts such as ionic liquids may be utilized. The magnesium salt dissociates in the solvent to Mg electroactive species BH4− and Mg2+.