The solid solutions of the (1-x)Na0.5Bi0.5TiO₃-xNa0.5K0.5NbO₃ system were produced by the conventional ceramic technology using mechanical activation of the synthesized product. It was found that in the (1-x)Na0.5Bi0.5TiO₃-xNa0.5K0.5NbO₃ system at room temperature, a number of morphotropic phase transitions occur: rhombohedral → cubic → tetragonal → monoclinic phases. The introduction of a small amount of Na0.5K0.5NbO₃ leads to an increase in the temperature stability of the dielectric properties of ceramics. A change in the relaxor properties of the solid solutions of the (1-x)Na0.5Bi0.5TiO₃-xNa0.5K0.5NbO₃ system was shown. The increase in energy density and energy efficiency was found at additive 10mol.% of Na0.5K0.5NbO₃.