The particle size and morphology of hydrothermally synthesised lead zirconate titanate (PZT) powders can be controlled by concentrations of the mineraliser such as potassium hydroxide (KOH), and the hydrothermal synthesis temperature and time, which all influence the particle nucleation and growth mechanisms. The mineraliser is crucial in facilitating both the in-situ transformation process during the nucleation stage and the nuclei-coagulation process during the subsequent growth stage. Its concentration must be high enough to ensure the formation of only pure perovskite PZT particles but low enough to prevent excessive PZT particle growth. The minimum necessary mineraliser concentration has, however, strong dependence on both the hydrothermal synthesis temperature and chemical environment in hydrothermal solution. Thus, perovskite PZT powders with ca. 200 nm particle size and narrow particle size distribution can be synthesised hydrothermally at 300degreesC using KOH as a mineraliser with a minimum concentration of 0.4 M. (C) 2004 Kluwer Academic Publishers.