The 0.95(Na0.5K0.5)NbO3-0.05SrTiO(3) (0.95NKN-0.05ST) ceramics formed in this study had a porous microstructure with small grains and low piezoelectric properties due to their low density. However, when a small amount of Na2O was intentionally subtracted from the 0.95NKN-0.05ST ceramics, a liquid phase was formed, which led to increased density and grain size. Piezoelectric properties were also improved for the Na2O-subtracted 0.95NKN-0.05ST ceramics. The increased density and grain size were responsible for the enhancement of the piezoelectric properties. In particular, the 0.95(Na0.49K0.5)NbO2.995-0.05ST ceramics showed high piezoelectric properties of d(33)=220, k(p)=0.4, Q(m)=72, and epsilon(T)(3)/epsilon(o)=1447, thereby demonstrating their promising potential as a candidate material for application to lead-free piezoelectric ceramics.