The structures of Ni clusters formed on a highly-stepped TiO2(110) surface were studied by polarization-dependent total reflection fluorescence X-ray absorption fine structure analysis. When 0.8 monolayers of Ni were deposited, three-dimensional Ni clusters with 1-2 nm diameters and heights less than 1 nm were formed. Conversely, when 0.07 monolayers of Ni were deposited, an anisotropic Ni trimer with a Ni-Ni distance of 0.260 nm was created at the [001] step. We revealed that the surface modification to enhance the metal-anion interaction can control the deposited metal structure. (C) 2013 Elsevier B.V. All rights reserved.