Deuterium ions of 100 keV were implanted into proton conductive perovskite oxides, such as SrCeO 3 (5% Yb), BaCeO 3 (10% Y), SrZrO 3 (10% Yb) and CaZrO 3 (10% In) with the thickness of 0.15–0.5 mm to a dose of ∼10 18/cm 2 at room temperature. The depth profiles of D were analyzed using the 3 He (D, 4 He )p nuclear reaction. The depth profile of D retained at the front (irradiated) surface shows a broad peak. For Y or Yb doped SrCeO 3, BaCeO 3 and SrZrO 3, the D depth profiles show tails into the sample, and a small but non negligible amount of D was detected at the back surface. These results indicate anomalous penetration of D through these samples.