The effect of sintering condition on structure, microstructure, and ferroelectric properties of (K0.44Na0.52Li0.04) (Nb0.86Ta0.10Sb0.04)- O₃ (KNL–NTS) has been investigated. Ceramic powders have been synthesized by the solid-state reaction method and sintered at different temperatures (1115∘C, 1125∘C, and 1140∘C). Then, samples were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. Through XRD results, the perovskite structure and small peaks corresponding to a secondary phase were detected. Ceramics processed at the highest temperatures showed higher densities and good piezoelectric properties (d33, Kp, and Kt), particularly specimens sintered at 1125∘C presented the highest piezoelectric performance.The effect of sintering condition on structure, microstructure, and ferroelectric properties of (K0.44Na0.52Li0.04) (Nb0.86Ta0.10Sb0.04)- O₃ (KNL–NTS) has been investigated. Ceramic powders have been synthesized by the solid-state reaction method and sintered at different temperatures (1115∘C, 1125∘C, and 1140∘C). Then, samples were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. Through XRD results, the perovskite structure and small peaks corresponding to a secondary phase were detected. Ceramics processed at the highest temperatures showed higher densities and good piezoelectric properties (d33, Kp, and Kt), particularly specimens sintered at 1125∘C presented the highest piezoelectric performance.