In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relativelyhigh temperature of 350℃ in order to eliminate surface oxide layers, which are the main obstacles for fabricating anano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure beforeand after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patternsusing the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD lineprofile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reduc-tion treated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nano-scale powders was produced and Vickers micro-hardness was measured to verify the potential of the powders as thebasis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of theparticles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results dem-onstrate the usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders isachieved.