Methods of forming metal alkoxides and methods of forming precursor solutions of metal alkoxides suitable for the coating of glass in the manufacture of electrochromic devices are disclosed. The method of forming metal alkoxides involves dissolving the metal halide in an anhydrous solvent and reacting it with an alcohol and (together with the addition of the alcohol or subsequently) adding an epoxide, and then evaporating-off the volatile components of the reaction product to leave a solid metal alkoxide that is substantially free of halide. The alkoxide may then be dissolved in a solvent including an alcohol (preferably ethanol) containing a small proportion of water to produce a precursor solution suitable for coating glass, the coating then being hydrolyzed to form a sol-gel and then baked to remove volatile components and to yield a thin layer of metal oxide.