The preparation of mesoporous tungsten trioxide from tungstic acid and tungstic hexaethoxide precursors containing an added organic stabiliser via a sol–gel method is reported. The effect of annealing temperature and precursor species on the photoelectrochemical performance and the electrochromic colouration efficiencies has been discussed with the help of the characterisation of crystalline structure (through Raman microscopy) and surface morphology (through SEM imaging). To cite this article: R. Solarska et al., C. R. Chimie 9 (2006) .