Aimed at developing practical protonic conductors with high reliability and conductivity, we initially investigated endurance against moisture for various protonic conductors of perovskite-type ceramics by placing samples in boiling water and in steam. Endurance against moisture involves the density and homogeneity of the sinters, Compounds containing Ce were affected by moisture and compounds containing Zr were hardly affected. Consequently, protonic conductors that have practical durability against moisture and high conductivity, such as BaZr0.6Ce0.2Gd0.2O3 and BaZr0.4Ce0.4In0.2O3, were prepared.