Epitaxial Cu(001) layers were deposited on MgO(001) substrates by magnetron sputtering and the atomic structure of the Cu-MgO interface was characterized by spherical aberration (C-S)-corrected high-resolution transmission electron microscopy (HRTEM). The interface structure and the misfit dislocation network were determined by imaging in both the < 100 > and < 110 > directions. The dislocation network was found to lie along the < 100 > directions with a Burgers vector of 1/2 a(Cu) < 100 > deduced from HRTEM images and geometrical phase analysis. The dislocations do not fully accommodate the lattice mismatch, yielding residual stress at the interface and an elongation of the Cu lattice along the [001] direction. (C) 2010 Elsevier B.V. All rights reserved.