Templated synthesis of poly(cyclotriphosphaze-co-4,4 -sulonyldiphenol) nanotubes (see figure) via a one-pot approach was achieved by the in situ formation of triethylammonium chloride nanocrystals during the polymerization. The triethylammonium chloride templates can eventually be removed by washing with water. The dimensions of the nanotubes can be controlled by modification of the experimental conditions.