Ba(0.5)Sr(0.5)TiO(3) (BST) thin films were deposited by rf magnetron sputtering using a Ba(0.5)Sr(0.5)TiO(3) target in pure Argon on two electrodes (Pt and RuO(2)) at room temperature. The interface formation between BST and bottom electrode (Pt or RuO(2)) was investigated by XPS for thicknesses in the 1 to 50 nm range. The chemical composition of the BST layers can be modified by the electrode nature over the first five nanometers. A 1 h ex-situ annealing, under flowing oxygen at 600 degrees C, was necessary to obtain crystallized 150 nm thick BST films, as evidenced by XRD and TEM analysis. (C) 2010 Elsevier B.V. All rights reserved.