Single phase Sr substituted BaZr0.1Ti0.9O3 (also known as BZT) ceramics with a formula Ba1-xSr xZr0.1Ti0.9O3 (x=0.10, 0.20, 0.30, 0.40 and 0.50) are prepared using a solid state reaction of mixed oxides at 1250 °C for 15 h. Analysis of XRD patterns of the ceramic powders show that Sr substitutes into Ba sites and reduces the lattice parameter. The powders are sintered at 1600 °C for 6 h to investigate the microstructure and functional properties. It is found that strontium substitution significantly modifies the microstructure and greatly influences the dielectric properties. The increase in Sr content reduces the ceramic grain size and results in spherical grains. With an increase in Sr content, the Curie temperature is lowered, and the relative permittivity maximum is increased and broadened. In Ba1-xSr xZr0.1Ti0.9O3 with x=0.30, the relative permittivity reached a maximum of 26600 and with further increase of Sr content, the relative permittivity is lowered and the phase transition is found to be broad and diffused. The ferroelectric hysteresis characteristics are discussed in detail. © 2007 Springer-Verlag.