We report the brilliant piezoelectric and dielectric properties of (Na0.5K0.5)NbO3 (NKN)-based materials and consider a promising candidate as a lead-free piezoelectric ceramic. However, because of volatile characterization of potassium and sodium oxide, the difficulty of sintering condition of NKN ceramics has been significantly issued. Therefore, we focused on sintering aids. To suppress volatilization and improve the sintering condition, other perovskite type's compounds and various sintering aids were added to NKN ceramics. We fabricated the 0.98(Na0.5K0.5)NbO3-0.02Li(0.04)(Sb0.06Ta0.1)O-3 (0.98NKN-0.02LST) ceramic by conventional solid-state reaction, and investigated the effects of various sintering aids (Ag2O, CuO, CeO2, MgO, MnO, ZnO) on the piezoelectric, dielectric, and structural properties of the 0.98NKN-0.02LST ceramic. All samples showed more outstanding properties than NKN ceramics. These results indicate that the 0.98NKN-0.02LST ceramics doped with various sintering aids is a promising candidate as a lead-free piezoelectric ceramic. (C) 2014 Elsevier Ltd. All rights reserved.