PbTiO3 thin films were prepared from alkoxide solution precursors and crystallized onto Pt/TiO2/SiO2/Si substrates. Microscopy observations revealed that the complexity of the domain walls structure decreased with the grain size. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in details. A shift of the temperature of the dielectric permittivity maximum due to stresses in the plane of films has been observed. Electrostrictive M and Q coefficients were estimated by measuring strain as a function of the ac electric field amplitude. The d(33) vs E-dc loops are rectangular with a maximum weak field piezoelectric d(33) coefficient equal to 65 pm/V. The dielectric permittivity and piezoelectric nonlinearities can be explained by taking into account domain-walls contributions. Dielectric and piezoelectric aging was investigated. It was found that both coefficients follow logarithmic time dependence, with comparable rates. The aging behavior in the PT films is thus qualitatively closer to that in ceramics than in thin films of lead zirconate titanate.(C) 2002 American Institute of Physics.