Ni clusters grown on SrTiO3 (0 0 1) and (1 1 0) substrates were studied with UHV-TEM. Before Ni deposition, both surfaces were cleaned effectively by electron beam annealing and showed atomic level flatness. Both surfaces seemed to have simple 1 x 1 structures. SrTiO3 (1 1 0) substrates are supposed to have O-vacancies on surfaces and inside. Ni clusters grow about 2-5 nm in sizes, and their interfacial structures and morphologies depend on substrate surface orientations. While clusters on SrTiO3 (0 0 1) grow with cube-on-cube epitaxial relationship, those on SrTiO3 (1 1 0) have two kinds of interfaces. In both cases, most of the clusters match the Winterbottom construction. On SrTiO3 (0 0 1) surfaces this appears as truncated pyramids. On SrTiO3 (1 1 0) surfaces they are either huts or hexagons. Those clusters are under the condition of partial wetting. Interface bonding energies are estimated based on their morphologies. (C) 2014 Elsevier B.V. All rights reserved.