Most of the chemistry-based preparation routes for bismuth titanate (BIT) involve calcination at elevated temperatures in order to realize precursor-to-ceramic conversion. In a completely different approach using an amorphous BIT hydroxide precursor, nanocrystalline particles of layered perovskite BIT are synthesized by mechanical activation, skipping the detrimental crystallite coarsening and particle aggregation encountered at high temperatures. Mechanical activation leads to nucleation and steady growth of BIT crystallites in the amorphous precursor matrix, while Bi2O3 is involved as an intermediate transitional phase. The activation-derived BIT particles demonstrate a rounded morphology of similar to50 nm in size. This is in contrast to the BIT derived from calcination of the coprecipitated precursor at 600degreesC that is dominated by coarsened platelike particles. The former is sintered to a density of > 95% theoretical at 875degreesC for 2 h, leading to a dielectric constant of similar to1260 when measured at 1 MHz and the Curie temperature of 646degreesC.