Modified tungsten oxide films by vanadium oxide provide neutrally coloring electrochromic electrodes for smart windows technology. In this study W-V-O mixed oxide films were fabricated by Nd:YAG pulsed laser deposition (PLD), lambda = 1064 nm, from mixed pressed powders of (WO(3))(1-x)(V(2)O(5))(x), x = 0, 0.09, 0.17, 0.23, 0.29 and 0.33, at 13.3 Pa oxygen partial pressure and 200 degrees C temperature on glass substrates. X-ray photoelectron spectroscopy (XPS) revealed V(5+), V(4+), W(6+) and W(5+) surface oxide states, where the ratio of W(5+)/W(6+) enhances by the amount of vanadium in the films. Surface morphology was studied by scanning electron microscope (SEM) and optical properties by transmission-reflection spectra. Results showed that films with a low amount of vanadium oxide have better porosity and higher optical band gaps. The gasochromic response to hydrogen gas exposure was found better for x = 0.09 in the sense of both deeper and faster coloring. Weak responses of samples with more vanadium oxide were attributed to higher amounts of W(5+) in the films and also to lower porosity. (c) 2008 Elsevier B.V. All rights reserved.