Fine, homogeneous lead lanthanum zirconate titanate (PLZT) powder prepared by the hydrolysis of an aqueous nitrate solution with ammonia gas exhibits high reactivity when calcined. The minimum temperature for crystal formation in PLZT is 400°C. The kinetics of crystallization between 400° and 600°C are studied isothermally by XRD. The isothermal crystallization process is best fitted to a first‐order equation derived for a random, nucleation‐controlled system on a large number of small particles with an activation energy of 297 kJ/mol. Characterization of the powder by XRD line‐broadening and BET surface‐area examination in the range 400° to 500°C shows a microstructure consisting of ∼20‐nm subunits agglomerated into ∼60‐nm particles. Each subunit evidently generates a single nucleus, which grows