Recently, a method to produce bulk quantities of pure multiwall WS2 nanotubes, which could reach several microns in length, has been developed. A detailed study of the growth mechanism of these WS2 nanotubes has been undertaken, which is reported hereby. A series of experiments were conducted to define the key parameters, which determine the shape of the WS2 nanotubes. An alternative approach for the synthesis of WS2 nanotubes, starting from long WO3-x nanowhiskers, which can be extended for the synthesis of other nanotubes, is described as well.