BaTiO3ceramics with grain sizes of 0.6 to 6 mm and relative densities of 89% to 92% were prepared by hot forging and conventional sintering from high‐purity oxalate‐derived powder. The aging of both the dielectric constant and the dielectric loss was examined with respect to grain size, temperature, and frequency. It is suggested that the main aging mechanism in coarse‐grained BaTiO3is the aging of hysteretic domain wall motion. The dielectric aging is a thermally activated process and shows two aging rates when observed at a temperature of 8°C for coarse‐grained