Cold-pressed pellets were prepared from ATiO(3)-MF2-LiF mixtures (A=Sr, Ba; M=Ca, Sr, Ph) and air-fired at 1223 or 1273 K for 2 h. X-ray diffraction analysis were carried out to control the purity and to identify the different phases. Each sample was a perovskite single phase. Superlattice reflections with an orthorhombic symmetry were detected for SrTiO3 compounds whereas no significant change was observed in the structure of BaTiO3 materials. The ceramic microstructure was systematically characterized by scanning electron microscopy. Dielectric measurements were performed as a function of temperature (123 K less than or equal to T less than or equal to 473 K) and frequency (20 Hz less than or equal to f less than or equal to 10(9) Hz). At low frequencies, a diffuse ferroelectric phase transition occurred for (Ba, M)(Ti, Li)(O, F)(3) ceramics. The room temperature frequency dependence of the complex permittivity has shown a resonance phenomenon for (Sr, M)(Ti, Li)(O, F)(3) phases in the range 2 x 10(8) - 5 x 10(8) Hz and a dielectric relaxation in the range 9 x 10(6) - 3 x 10(7) Hz for BaTiO3 related materials. (C) 1999 Elsevier Science S.A. All rights reserved.