Infrared spectra for the O-H stretching vibration, v(OH), region were studied for Sc- and Y-doped SrZrO3 and Y-doped BaZrO3 ceramics. For Sc-doped SrZrO3 and Y-doped BaZrO3, two intense nOH bands at ∼ 3300 and ∼ 3030 cm(-1) were observed for the low doping level. With increasing doping level, two nOH bands at ∼ 2450 and 1900 cm(-1) appeared in addition to the bands at ∼ 3300 and ∼ 3030 cm(-1) and increased their intensities. However, intensities of the bands at ∼ 2450 and ∼ 1900 cm(-1) were considerably smaller than those of the bands at ∼ 3300 and ∼ 3030 cm(-1). In contrast to Sc-doped SrZrO3, four bands at ∼ 3300, ∼ 3030, ∼ 2450, and ∼ 1900 cm(-1) were observed for the low doping level in Y- doped SrZrO3; furthermore, the intensities of the four bands were comparable and independent of Y-doping level. Thus, the two bands at ∼ 3300 and ∼ 3030 cm(-1) were attributable to the proton bonded to the oxygen between dopant M-III and the host Zr ions, i. e., M-III-OH-Zr. The bands at ∼ 2450 and ∼ 1900 cm(-1) were attributed to the proton bonded to the oxygen between the two dopants, i.e., M-III-OH-M-III The present results revealed that dopant Y in SrZrO3 aggregated on an atomic scale and formed the YO6 cluster even for the low doping level. © 2005 The Electrochemical Society. All rights reserved.