The stability of lead titanate zirconate (PZT) precursor solutions is analyzed by taking into account the time evolution of their particles size distributions and pH. Solutions were synthesized by a hybrid sol-gel route carefully chosen in order to attain the maximum coordination number for all of the (Zr/Ti)(4+) cations involved in the chemical reaction. Dynamic light scattering (DLS) and pH measurements were carried out for samples up to 4 months old and some noticeable features were detected in all cases: i.e. mean particles size (< d >) was well below 10 nm, particles size distribution functions tend to become unimodal only after a few days from synthesis and, after some time, the pH evolution seems not to influence the values of mean particles size. DLS results were also used to formulate a fairly accurate physical description of our systems on the basis of the classical Smoluchowski theory for colloidal dispersions in the approximation of van Dongen-Ernst. (C) 2010 Elsevier B.V. All rights reserved.