In this work, nanocrystalline hexagonal tungsten oxide was prepared by acidic precipitation from sodium tungstate solution. TEM studies of nanopowders showed that the average size of the hexagonal nanoparticles is 30-50 nm. Novel nanocomposites were prepared by embedding a low amount of gold decorated carbon nanotubes into the hex-WO3 matrix. The addition of MWCNTs lowered the temperature range of sensitivity of hex-WO3 nanocomposites to NO2 hazardous gas. The sensitivity of hex - WO3 with Au-decorated MWCNTs to NO2 is at the temperature range between 25°C and 250°C.