First-principles calculations were carried out to examine the chemical stability and proton conductivity of A-site-doped BaZrO3. In a previous study, we investigated these two properties of B-site-doped BaZrO3. [RSC Adv. 3 [10] 3333-3341 (2013)] Here, we investigated BaZrO3 doped with K, Rb, and Cs at A-sites. We found that K-doped BaZrO3 showed the highest proton conductivity and chemical stability among the examined A-site dopants with respect to the carbonate formation reaction. Remarkably, there is a lack of a trade-off relationship between chemical stability and proton conductivity in A-site-doped BaZrO3.