Carbon-coated PbTe nanowires were successfully synthesized via a one-step hydrothermal process using ascorbic acid as a reducing agent and carbonization source. The average diameter of PbTe core nanowires and thickness of carbon sheaths are about 25 and 8 nm, respectively. Sequential mechanism for the phase formation, shape evolution, and carbon sheath formation was also investigated. Te nanowires were initially grown and then amorphous carbon sheaths were formed on the surface of the grown Te nanowires. At the same time, Pb(2+) ions diffused into the carbon sheaths and react with Te nanowire, resulting in the formation of carbon-coated PbTe nanowires. Additionally, the size and shape of the PbTe nanowires were found to be determined during the initial stage of Te formation.