Barium titanate (BaTiO3) has been doped in situ with 5 mol% thulium by a sol–gel method. The as-prepared gel powder consists of nanosized grains (20–30 nm) and crystallizes on the cubic BaTiO3 lattice, at 700°C. Ba0.95Tm0.05TiO3 ceramics derived from this powder have tetragonal perovskite structure and contain a small amount of Tm2Ti2O7 pyrochlore phase. These ceramics exhibit dielectric constants of 4282–3240 and dielectric loss (tan δ) of 0.1077–0.0161 at Curie temperature Tc=132°C and at 10 Hz–100 kHz, respectively. For a drive voltage of 400 V, the hysteresis loop recorded at the frequency of 100 Hz shows a remnant polarization (Pr) value of 76 μC/cm2 and a coercive field (Ec) of 124 V and for 1 kHz a remnant polarization (Pr) value of 58 μC/cm2 and a coercive field (Ec) of 116 V.