Stress corrosion cracking (SCC) in water and hydrogen-induced cracking (HIC) of an alumina ceramic during dynamical charging with various current densities were investigated using constant load specimens. The results showed that hydrogen-induced intergranular failure occurred, and the normalized threshold stress intensity of HIC, K-IH/K-IC, decreased linearly with the logarithm of hydrogen concentration C-0, i.e., K-IH/K-IC = 1.1-0.36InC(0). The normalized threshold stress intensity of SCC in water was K-ISCC/K-IC = 0.64, which was below that of HIC during charging with i <= 20 mA/cm(2).