Unique PbS nanowires with x-shaped cross sections, with diameters in the range of 300-800 nm with an average of 598 nm (sigma = +/- 21.7%), and lengths of up to several tens of micrometers, have been made by a solventless method. Such nanowires show high adsorptivities of the PbS nanooctahedra, which can be washed off by ultrasound. The suitable precursor is obtained from a Pb(NO3)(2)/Octanoate/ethylenediamine/dodecanethiol molar ratio of 1:21: 1.6, and the PbS nanowires are produced by the thermolysis of such precursors at 280 degrees C for 1 hour. The X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterizations of the products and the keys of the morphological control have been reported. For the formation of such products, two cooperative effects are found to be crucial, the roles of ethylenediamine and a second salt, lead octanonate.