One of the urgent tasks of applied materials science is the creation of novel high-effective materials with target properties. In the area of energy systems, there is a problem in the conversion of chemical energy to electricity without mechanical work. Hydrogen energy provides a way using electrochemical devices such as protonic ceramic fuel cells. Novel advanced proton-conducting materials with the top characteristics of target properties are strictly needed. Layered perovskites are a novel and promising class of protonic conductors. In this work, the layered perovskite BaLa0.9Pr0.1InO4 was obtained and investigated as a protonic conductor for the first time. The possibility for water intercalation and proton transport is proved. It was shown that isovalent doping Pr3+ -> La3+ leads to an increase in the crystal lattice size, proton concentration and proton mobility. The proton conductivity value for doped BaLa0.9Pr0.1InO4 composition is 18 times greater than for undoped BaLaInO4 composition. Layered perovskites based on BaLaInO4 are promising materials for application in proton-conducting electrochemical devices.