The nucleation and initial growth of Fe on the (1 x 1) rutile TiO2(110) substrate as a function of coverage and annealing temperature were studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The deposition of 0.03 ML-0.3 ML (monolayer) of Fe resulted in the growth of one-, two-and three-dimensional iron clusters. Surface annealing at 373 K and 473 K resulted in a moderate sintering of the Fe clusters, whereas annealing at higher temperatures led to Fe incorporation into the substrate. The analysis of the Fe 2p core excitations showed that even after room temperature processes, iron was partially oxidized at the iron/titania interface. (C) 2017 Elsevier B.V. All rights reserved.