Water-induced degradation of barium titanate (BTO) ceramics has been investigated using electrochemical hydrogen charging, in which the silver electrodes of BTO ceramic specimens are made cathodes in a 0.01M NaOH solution to evolve hydrogen by electrolysis of water. After 80 h of treatment, the resistance of BTO decreases by similar to3 orders of magnitude, and the dielectric loss obviously increases. The degradation can be explained by the reduction reaction of atomic hydrogen with BTO. Hydrogen acts as a donor in BTO, and electrons are formed by the reduction. It is proposed that the reduction reaction of atomic hydrogen at ambient temperature by electrolysis of water is an important origin for degradation of BTO-based ceramic devices.