An improved chemical route is described to precipitate quantitatively a molecular precursor lead zirconyl oxalate tetrahydrate, PbZrO(C2O4)2·4H2O (PZO) at room temperature. In this route, soluble ammonium zirconyl oxalate, (NH4)2ZrO(C2O4)2 (AZO), is initially prepared by chemical reaction of 0.1-M solution of zirconyl nitrate with 0.2-M solution of ammonium oxalate. The anionic species ZrO(C2O4)2-2 thus obtained is exchanged by adding equimolar solution of lead acetate to precipitate single-phase PZO with higher yield. The improvement in the presently described route is to drive exchange reaction to its completion by suitably manoeuvring the choice of precursor, pH and reaction conditions, in such a way that single-phase PZO is precipitated without any destabilization of anionic species ZrO(C2O4)2-2. The pyrolysis of PZO produced stoichiometric, monophasic, orthorhombic PbZrO3 (PZ) powders at temperature T=700°C. Various physico-chemical techniques were used to characterize both molecular precursor PZO as well as PZ powders obtained by its pyrolysis. All our experimental results related to the synthesis and characterization of these powders are presented in this paper. © 2001 Elsevier Science B.V. All rights reserved.