Pb(Zr0.4Ti0.6)O-3 [PZT(40/60)] thin films were deposited onto LaNiO3 (LNO) coated Si substrates by sol-gel technique. Three kinds of gases, air, O-2 and N-2, were used as the annealing ambient. The effect of the annealing ambient on their structure and ferroelectric properties was investigated. The results showed that both the films annealed in air and O-2 were the complete perovskite phase with (1 0 0) preferential orientation, while those annealed in N-2 were random orientation including some pyrochlore phases. As compared with the air ambient, either too much O-2 or too much N-2 was detrimental to the ferroelectric properties of PZT films. The difference in structure and ferroelectric properties was mainly associated with the intermediate phases and the concentration of domain pinning centers in the films. (C) 2004 Elsevier Ltd. All rights reserved.