(1-x)(Na0.5K0.5)NbO3-xBaTiO(3) ceramics were prepared by a solid state reaction approach, and their dielectric and ferroelectric properties were evaluated together with the crystal structure. Three phase transitions at T-t1, T-t2 and TO were observed by the combination of DTA analysis and dielectric characterization. These phase transitions corresponded to those of (Na0.5K0.5)NbO3, and they were greatly pulled down by forming solid solution with BaTiO3. The phase transition around T-t1 was incompletely diffusive and the appearance of diffusiveness of non ferro-paraelectric phase transition was an exception. The hysteresis loops changed their shapes from "square" into "thin square" with increasing x. (C) 2005 Published by Elsevier Ltd.