Porous copper was produced by electrolytic dealloying of a Cu-Mn alloy (Incramute: Cu, 40-48 wt. % Mn, 1.4-2.3 wt. % Al) conducted in a 0.3 N-NaCl solution at a potential of −0.2 V (SCE). The dealloying time needed for the as-received cold-rolled specimen (50 h) is shorter than that of the annealed specimen (850 °C for 2 h). The pore size, about 1 μm, of the dealloyed cold-rolled specimen is bigger than that, about 0.1 μm, of the dealloyed specimen after annealing. This is probably because annealing reduced the phase inhomogeneity and removed the rolling effects.