Hollow spheres of lead zirconate titanate (PZT) [chemical formula Pb(Zr0.52Ti0.48O3)], with outer diameter of 1-2 mm and a wall thickness of about 100 mu m, were fabricated by gellation of a PZT sol inside solid polymer spheres and then burning the polymer out. Monomodally sized polyacrylamide spheres, with diameter 1.40-1.90 mm, were soaked in a PZT sol, prepared by dissolving Pb(NO3)(2), zirconium n-butoxide and titanium isopropoxide in N,N-dimethylformamide. The absorbed sol was then gelled beneath the surface of the polymer sphere by the action of NH3. Upon calcination of the spheres at 850 degrees C for 4 h in air, hollow spheres of pure PZT perovskite phase (as identified by X-ray diffraction patterns) were obtained. The density of the hollow spheres was 1.13 g cm(-3), while that of the wall of the spheres was 3.10 g cm(-3). The scanning electron microscopic examination of the broken spheres showed that the inner surface of the spheres contained rib-like structures, which provided strength to the hollow spheres. The planar coupling factor, k(p), of six hollow spheres, placed at a close-packed arrangement in a plane, was 0.22, indicating the possibility of fabrication of low-density transducer arrays.