Chalcopyrite copper indium sulfide (CuInS2, CIS) has a bandgap that is optimal for a solar energy conversion material. In this paper, we used a polymer-type ion release source to control the precursor concentration of the hydrothermal system to grow CIS nanowires. The analytical results indicate that the reaction process is based on the formation of CuS binary compound, which is then followed by indium intercalation, which induces the formation of the CIS chalcopyrite crystal structure. The products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The CIS nanowires were 100-300 nm in diameter and 2-5 mu m in length.