The optical properties of arrays of An nanorods were studied by specular reflectance spectroscopy. The spectra were dominated by the surface plasmon modes of the An nanoarrays superimposed on the effects of interference through the films. The longitudinal plasmon resonance moved to longer wavelength as the aspect ratio of the nanorods increased. The reflectance spectra were modelled by applying the Maxwell-Gamett approximation to a uniaxial thin film (composite Au/alumina) and this yielded a good match to the experimental data. SERS spectra on the Au nanorod arrays were recorded at different externally applied potentials and significant differences with respect to an electrochemically roughened Au electrode were revealed. These have been attributed to the nature of the composite nanoarrays, both their nanostructuring into rods and the regular arrangement of these rods. (c) 2007 Elsevier Ltd. All rights reserved.