## 1 Introduction  
Applied materials science plays an important role in the development of various areas of human life. Critical areas such as medicine, energy and mechanical engineering cannot develop without the creation of new materials with targeted properties. Ceramic materials are required for very different needs such as medical applications (endoprosthetics) [1; 2; 3; 4; 5; 6] and components for various electrochemical devices [7; 8; 9; 10; 11; 12], as examples. The high priority of sustainable development necessitates the development of advanced energy technologies, one of them being hydrogen energy [13; 14; 15; 16]. The switchover to renewable energy is, actually, not only for increasing energetically efficiency, but, also, due to the pursuit in decreasing climate changes and the lowering of cases of respiratory diseases [17; 18; 19; 20; 21; 22; 23]. Hydrogen energy is considered as an actual, sustainable and promising approach for energy generation [24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35]. This industry includes aspects such as the production, transportation and use of hydrogen as an energy source. The conversion of the chemical energy of hydrogen oxidation to electrical energy can be implemented using electrochemical devices such as protonic ceramic fuel cells [36; 37; 38; 39; 40; 41]. This requires new high-effective materials such as electrodes, electrolytes and interconnectors with good compatibility between each other. The traditional and most investigated proton-conducting materials are barium cerate zirconates BaCeO\({}_{3}\)-BaZrO\({}_{3}\), which are characterized by perovskite structure [42; 43]. However, they are characterized by a relatively low concentration of protons and low chemical resistance to carbon dioxide. Consequently, novel advanced proton-conducting materials with top characteristics of target properties are strictly needed.  
Layered perovskite structure is related to classical perovskite structure. The main difference is the separation of the perovskite framework by the layers with different structures.  
Layered perovskites with the general formula AA\({}_{n}\)B\({}_{n}\)O\({}_{3n+1}\) belong to members of layered perovskite family such as compositions with the Ruddlesden-Popper structure. Perovskite slabs A\({}^{\prime}\)BO\({}_{3}\) are divided by the rock salt layers AO in this structural type, and the existence of compositions with a different \"n\" is possible. Layered structures provide a concentration of protons an order of magnitude higher than that of classic perovskites. The realization of proton transport was proved for monolayer perovskites such as BaNdInO\({}_{4}\)[44; 45; 46; 47; 48], BaNdScO\({}_{4}\)[49], SrLaInO\({}_{4}\)[50; 51; 52; 53; 54], BaLaInO\({}_{4}\)[55; 56; 57; 58; 59; 60] and compositions based on them in the last few years [61]. Such compositions can be potentially used as electrolytic materials in the proton-conducting fuel cells. Various types of doping, including cationic [62] and oxyanionic [63], were investigated. However, the substitutions were implemented by the ions with a stable oxidation state. Meanwhile, the introduction of ions capable of changing their valence can provide control over the contributions of the electronic and ionic components of conductivity. In the future, this can ensure the creation of electrode and electrolyte materials with the same crystal structure and similar chemical composition, which should provide excellent compatibility. In this work, a Pr-doped ceramic material based on BaLaInO\({}_{4}\) was obtained and investigated for the first time. The possibility of protonic transport was revealed.