The present work describes a novel process for the elaboration of a ceramic material. Y-doped barium zirconate, an electrolyte material for Protonic Ceramic Fuel cell, was synthesized by a continuous hydrothermal process in supercritical conditions (410 • C/30.0 MPa) using nitrate precursors and NaOH reactants. The use of supercritical water allowed the formation of particles of about 50 nm in diameter with a narrow size distribution. X-Ray Diffraction examination revealed that a major perovskite phase with few BaCO 3 and YO(OH) impurities was obtained. BaCO 3 is assumed to form due to faster kinetics than Y-doped BaZrO 3 resulting in a Ba-deficient perovskite phase. The Ba-deficiency limits the incorporation of yttrium into the perovskite structure. However, a thermal treatment at 1000 • C for 1 h allows to homogenize the composition and thus to obtain the compound Ba 1.01 Zr 0.85 Y 0.15 O 3-δ .