Cesium ions were implanted at the energy of 300 keV in YSZ at 300 and 1025 K, with increasing fluences up to 5 x 10(16) cm(-2). Concentration profiles were determined by Rutherford Backscattering Spectrometry (RBS) measurements. Transmission Electron Microscopy (TEM) experiments were achieved to determine the nature of the damages and to characterize a predicted ternary phase of cesium zirconate. At 300 K, amorphization occurs at high Cs-concentration (9 at.%) due to a chemical effect. TEM investigations performed after in situ post-annealing shows the recrystallization of YSZ concurrently with the cesium release. No precipitation of secondary phases was observed after annealing. With implantation performed at 1025 K, dislocation loops and bubbles were formed but the structure did not undergo amorphization. Dislocation rearrangement leads to the polygonization of the matrix. The cesium concentration reaches a saturation value of 1.5 at.%, and once more no precipitation is observed. (c) 2008 Elsevier B.V. All rights reserved.