The addition of a small amount of CuO to the 0.95(Na(0.5)K(0.5))NbO(3)-0.05CaTiO(3) (0.95NKN-0.05CT) ceramics sintered at 960 degrees C for 10 h produced a dense microstructure with large grains due to the liquid phase sintering. Due to the negligible Na(2)O evaporation, poling was easy for all specimens sintered at 960 degrees C. The piezoelectric properties of the specimens were considerably influenced by the relative density, grain size and liquid phase amount. The high piezoelectric properties of d(33) = 200 pC/N, k(p) = 0.37 epsilon(T)(3)/epsilon(0) = 1173 and Q(m) = 350 were obtained for the 0.95NKN-0.05CT ceramics containing 2.0 mol% CuO sintered at 960 degrees C for 10 h. Therefore, the 0.95NKN-0.05CT ceramics containing, a small amount of CuO are a good candidate material for lead-free piezoelectric ceramics. (C) 2008 Elsevier Ltd. All rights reserved.