Preliminary results are presented from the study of grain boundary structure in bulk nanocrystalline copper using high-resolution electron microscopy. A recently developed method of image analysis is applied to an experimental image of a grain boundary between two copper grains. Maps are produced of the fringe spacing and the local rotation of the lattice as a function of position in the image. The analysis of the fringe spacing shows that no oxide layer exists between the copper grains. This confirms that the surface oxide layer coating the copper particles can be eliminated during the formation of the bulk material. By studying the way the rotation of the lattice takes place across the grain boundary, an upper limit for the interface width is obtained. The reliability and accuracy of the results are discussed.