Abstract: The present invention concerns a zirconia in the form of a fine powder, to a zirconium hydroxycarbonate and to processes for their preparation. The zirconia has a chlorine content of at most 300 ppm and a sulphur content of at most 30 ppm, and is in the form of a powder constituted either by agglomerates with an average size of at most 1.5 &mgr;m that can be disintegrated into aggregates with an average size in the range 0.1 &mgr;m to 0.6 &mgr;m, or aggregates with an average size in the range 0.1 &mgr;m to 0.6 &mgr;m. The zirconium hydoxycarbonate has the same chlorine and sulphur contents and following calcining, it results in the zirconia with the characteristics defined above. The zirconia of the invention can be used to produce condensers or oxygen probes, or it can be used in preparing catalysts.