Fabrication of nanoporous coatings is investigated by a two-step process involving high power laser cladding of homogeneous Cu40Mn60 alloy coatings followed by selective electrochemical de-alloying. Cu-Mn alloy coatings with fine shape, low dilute ratio and refined microstructure are fabricated on mild steel by means of laser processing. The second dendrite arm spacing (SDAS) decreases with the increase of laser remelting speed. Auger mapping results indicate that nanoporous manganese is obtained by selective electrochemical etching of the less active Cu component owing to the passivation of the more active manganese in potassium nitrate solution. The microstructure and homogeneity of the precursor Cu40Mn60 alloys have a significant influence on the evolution of nanopores during selective electrochemical de-alloying. The surface morphology of the porous Mn is a ribbon-like structure with thickness up to 2 μm.