A pure, acicular lead titanate (PbTiO3) fine powder with a white color has been prepared by hydrothermal synthesis. It is a new phase of PbTiO3withI4 symmetry, cell parameters ofa= 12.358 Å andb= 14.541 Å, and a density of 6.80 g.cm−3. The influences of pH (12.5 to 14.4), Pb/Ti ratio (1.0 to 1.6) in the feedstock, reaction temperature (130° to 230°C), time (0.25 to 4 h), starting materials, and additives on the formation of acicular PbTiO3under hydrothermal conditions have been investigated. The acicular PbTiO3withI4 symmetry, referred to as the PX phase, can be converted to the perovskite‐type (PE phase) of PbTiO3at about 605°C while its acicular morphology is essentially unchanged. The preferable conditions for preparing pure acicular PX‐phase PbTiO3are that the pH is 13.0 to 14.0, Pb/Ti ratio is>1.3, reaction temperature is 170° to 200°C, time is 0.5 to 1.0 h, titanium butoxide (Ti[O(CH2)3CH3]4) is the starting material, and poly(vinyl alcohol) is an additive. The acicular grain of the PX phase is usually less than 100 nm in diameter and more than 1000