Aluminum is treated with an agent to prevent passivation of the aluminum during oxidation. The passivation preventing agent is a metal alloy containing gallium, preferably a eutectic alloy of gallium, indium and tin. The surface of the metallic aluminum is wetted with the eutectic alloy, suitably by scouring and/or immersion. The treated aluminum may be mixed with water, hydrogen peroxide or other suitable oxidizer in a controlled manner to produce hydrogen, heat, steam or oxygen for the use in power generation or chemical reactions. The passivation removal agent can be used in small quantities and is readily recoverable following the reaction.