Nanoporous metals are generally defined as metals with features in the pore structure in the range of 100 nm or less. Nanoporous copper (np-Cu) has recently attracted attention as an alternative to nanoporous gold or platinum. Our np-Cu is prepared by a three-step process: (i) in-situ alloying of aluminium/copper by laser powder bed fusion, often referred to as the 3D laser printing process, (ii) subsequent annealing at 530° C, followed by (iii) a de-alloying process to remove the aluminium from the bulk alloy. The properties of np-Cu including morphology, crystal structures and chemical composition were systematically characterized by X-ray diffraction and X-ray fluorescence spectroscopy while topography and composition of the surfaces were investigated by scanning electron microscopy (SEM). In addition, the pore size distribution and internal surface area of np-Cu are quantified using techniques such as microcomputed tomography (𝜇-CT) and mercury intrusion porosimetry. Although the composition of the domains in the alloy changes during the de-alloying process, these domains retain their spatial position and extent.