Hydrogen-induced modifications of oxide materials have started to trigger much interest in the field of hydrogen-related oxide materials. From both scientific and technological viewpoints, the sciences of hydrogen-induced modifications of hydrogen-related oxide materials need to be studied more extensively and intensively. Al2O3 and Y2O3 have been applied in many areas, e.g. thermal barrier coatings, tritium permeation barriers and refractory materials and so on. However, these structural materials are sometimes used in harsh reducing environments, which proposes strict requirements in the mechanical and electrical properties of the materials. However, the performance of YAlO3 in reducing atmospheres, i.e. the complex oxide of Y2O3 and Al2O3, has hardly been studied. Therefore, the stability of YAlO3 single crystals in hydrogen at high temperature was investigated in the present study. The results show that with increasing hydrogen treatment time, the hardness and electrical resistivity of YAlO3 decrease. The mechanism for hydrogen-induced modifications of the electrical properties and hardness of YAlO3 single crystals were analyzed through comparisons of X-ray diffraction patterns and infrared absorption spectra.