The electrodeposition of lanthanum hydroxide films onto nickel substrates in the presence of polyethylenimine (PEI) has been studied by infrared spectroscopy, x-ray photoelectron spectroscopy and atomic force microscopy with the aim of exploring the effectiveness of the technique and the chemistry of the deposited films. Maximum deposition rates were recorded for low concentrations of PEI with rates decreasing at higher PEI concentrations largely because of the poor structural integrity of the deposited films. Similarly, extending the deposition times did not improve film coverage as thicker films adhered less well to the nickel substrate. The deposited films were shown to contain co-deposited PEI with the concentration remaining constant within the films during deposition but changing linearly with PEI concentration in the depositing solution. (C) 2011 Elsevier B.V. All rights reserved.