Ceramics (1 - x) Ba(Ti1 - yZry)O-3 center dot xPbTiO(3)withx = 0,y = 0;x = 0,y = 0.05;x = 0.05,y = 0.05;x = 0.10,y = 0.05;x = 0.15,y = 0.05;x = 0.20,y = 0.05 were obtained by solid-state mixed oxide method at 1400 degrees C. Phase composition of the ceramic samples was determined by the Rietveld method using powder diffraction data. At the first stage, the refinement was done for the two most representative sections of the registered XRD patterns, namely: 2 theta = 44.6 degrees-46.2 degrees and 2 theta = 55.4 degrees-57.2 degrees. At the second stage, the refinement for the full XRD patterns was performed. The quantitative content of phases and their crystallographic data is determined. All samples contain a perovskite tetragonal phase (space group P4 mm). The cubic phase (space group Pm-3 m) is present in the samples withx = 0,y = 0;x = 0,y = 0.05;x = 0.05,y = 0.05;x = 0.10,y = 0.05. The orthorhombic phase (space group Amm2) is contained in the samples withx = 0,y = 0.05;x = 0.05,y = 0.05;x = 0.10,y = 0.05;x = 0.15,y = 0.05. Substitution of Ti for Zr in the tetragonal form of BaTiO(3)reduces the tetragonal distortion of the unit cell. Substitution of Ba for Pb increases the tetragonal distortion of the unit cell.