New (1−x)Ag 0.9 Li 0.1 NbO 3 –xBi 0.5 K 0.5 TiO 3 ceramics were synthesized and investigated by means of broadband dielectric spectroscopy (20Hz–37GHz), an X-ray and an SEM. It was demonstrated that the ferroelectric phase transition temperature does not monotonically decreases with Bi 0.5 K 0.5 TiO 3 concentration and the ferroelectric phase transition completely vanishes in 0.85Ag 0.9 Li 0.1 NbO 3 –0.15Bi 0.5 K 0.5 TiO 3 ceramics, where the relaxor behavior is observed. In contrast the antiferroelectric phase transition disappears in 0.9Ag 0.9 Li 0.1 NbO 3 –0.1Bi 0.5 K 0.5 TiO 3 ceramics, at room temperature these ceramics are close to a rhombohedral–tetragonal phase boundary. The static dielectric permittivity increases with Bi 0.5 K 0.5 TiO 3 concentration due to the increase of disorder in the system and gradual appearance of new excitations in the dielectric spectra: a microwave relaxation soft mode and dynamics of polar nanoregions.