Barium zirconium titanate ceramics, BaTi 1–x Zr x O 3 (x = 0–15 at % with a step of 2.5%) (BTZ x), were obtained by a sol-gel method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of zirconium ions affects the growth of the grain and remarkably changes the grain morphology. The effect of zirconium addition to BT on dielectric properties is analyzed. Increasing Zr content in the BaTiO 3-based compositions caused a decrease in the Curie temperature (T c) and the permittiv-ity increases. The Curie-Weiss law is well followed for the pure sample, but it is less respected in the case of BTZ 10 and the variation of the Curie Weiss constant as a function of frequency is similar to the variation of the dielectric constant. On the other hand, the application of the modified Uchino law, to the BTZ x materials, shows that the diffusion factor increases from 1.06 to 1.78 with increasing x from 0 to 0.15, implying a composition-induced diffuse transition.