The Seebeck effect of ZnO nanowires has been investigated with the future aim of building thermoelectric devices based on nanowire arrays for energy harvesting and using them in low-power portable electronics and autonomous sensor systems. Quasi monodimensional (1D) ZnO nanowires have been deposited on alumina substrates according to the recently proposed thermal evaporation process, which involves Vapour-Phase and Vapour-Liquid-Phase growth mechanisms. The Seebeck coefficient of ZnO nanowires has been successfully measured with a purposely- developed experimental set-up, confirming that the ZnO nanowires exhibit high thermoelectric coefficient.