Abstract: Disclosed is a method for forming a catalyst bed for catalytic decomposition of hydrogen peroxide, which uses 3-D printing techniques to form a porous metal backbone and treating the surface of the metal backbone to activate the surface, wherein the metal backbone is formed of a noble metal or a manganese complex. Also disclosed is a rocket engine having a 3D printed catalyst for catalytic decomposition of hydrogen peroxide, a fuel store, an oxidizer store, and a rocket engine, wherein the oxidizer is a stabilized solution of hydrogen peroxide, and a 3D printed catalyst bed.