The effect of sintering condition on structure, microstructure, and ferroelectric properties of (${\text{K}}_{0.44}$${\text{Na}}_{0.52}$${\text{Li}}_{0.04})$ (${\text{Nb}}_{0.86}$${\text{Ta}}_{0.10}$${\text{Sb}}_{0.04})$- O₃ (KNL–NTS) has been investigated. Ceramic powders have been synthesized by the solid-state reaction method and sintered at different temperatures (1115${}^{\circ }$C, 1125${}^{\circ }$C, and 1140${}^{\circ }$C). Then, samples were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. Through XRD results, the perovskite structure and small peaks corresponding to a secondary phase were detected. Ceramics processed at the highest temperatures showed higher densities and good piezoelectric properties ($d_{33}$, $K_p$, and $K_t)$, particularly specimens sintered at 1125${}^{\circ }$C presented the highest piezoelectric performance.The effect of sintering condition on structure, microstructure, and ferroelectric properties of (${\text{K}}_{0.44}$${\text{Na}}_{0.52}$${\text{Li}}_{0.04})$ (${\text{Nb}}_{0.86}$${\text{Ta}}_{0.10}$${\text{Sb}}_{0.04})$- O₃ (KNL–NTS) has been investigated. Ceramic powders have been synthesized by the solid-state reaction method and sintered at different temperatures (1115${}^{\circ }$C, 1125${}^{\circ }$C, and 1140${}^{\circ }$C). Then, samples were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. Through XRD results, the perovskite structure and small peaks corresponding to a secondary phase were detected. Ceramics processed at the highest temperatures showed higher densities and good piezoelectric properties ($d_{33}$, $K_p$, and $K_t)$, particularly specimens sintered at 1125${}^{\circ }$C presented the highest piezoelectric performance.