We studied NiO layers epitaxially grown on a stabilized MgO(1 1 1) substrate at various temperatures between 700degreesC and 900degreesC. The epitaxial growth and surface structures were investigated using reflection high energy electron diffraction, atomic force microscopy, X-ray, diffraction and high resolution transmission electron microscopy. The experiments indicate that nickel oxide tetrahedra with [100] facets have grown on the surface. We present the evolution of the surface morphology as a function of deposition temperature and thickness. The role of the surface energy minimization in the occurrence of tetrahedral islands is demonstrated. (C) 2002 Elsevier Science B.V. All rights reserved.