Pyrochlore-free 0.64Pb(Ni 1/3Nb 2/3)O 3–0.36PbTiO 3 (0.64PNN–0.36PT) powder has been successfully synthesized by only one calcination step using a coating method. The formation of pyrochlore phase is prevented by coating NiCO 3·2Ni(OH) 2·2H 2O on Nb 2O 5 particles. NiCO 3·2Ni(OH) 2·2H 2O-coated Nb 2O 5 powder is prepared by heterogeneous precipitation method. The coating structure is confirmed by transmission electron microscope (TEM) with energy dispersive spectroscope (EDS). Single calcination treatment of the coating powder mixed with appropriate amounts of Pb 3O 4 and TiO 2 powders at 900 °C for 2 h produces the pure-perovskite 0.64PNN–0.36PT powder. The elimination of the pyrochlore phase can be explained in terms of the separating of Pb 3O 4 and Nb 2O 5 by the NiCO 3·2Ni(OH) 2·2H 2O coating layer.