The aim of the project is to determine the relationship between the crystal structure and proton transport in selected groups of perovskite materials exhibiting mixed ionic-electronic conductivity. The materials under study are perovskite triple conducting oxides (TCO), which under certain conditions are able to conduct three types of charge carriers: electrons, oxygen ions, and protons. These compounds can be applied, among others, as positrodes in solid oxide fuel cells with proton conducting electrolyte (PCFC). The project provides a series of TCO studies in terms of structural changes and their influence on the thermodynamics of the proton uptake process. One of the factors strongly influencing that process is the tilting of oxygen-metal-oxygen bonds. To observe those changes, X-ray diffractometry and spectroscopic methods, such as EXAFS, will be employed. The results obtained by those methods will allow for a thorough analysis of the crystal structure, distances between specific atoms and the degree of tilting of metal-oxygen bonds. Valuable information will be the average oxidation state of transition metal atoms determined by the XANES method, which will also be initially determined by the XPS method. In order to analyze the hydration process of the investigated oxides, they will be studied using the thermogravimetry (TG) method, which will enable the determination of the concentration of proton defects. An important part of the project will be to perform measurements of transport properties in the tested materials using DC and AC techniques. Important information will be obtained using Electrical Conductivity Relaxation (ECR) method, which allows to determine the mobility of protons in the structure. The research planned for this project will have a significant impact on the development of Materials Engineering, in particular the field of proton conductors for use as a positrode in electrochemical devices. The research results will be published in international journals on the JCR list and presented at international conferences. As a part of the project, a measurement setup for measuring electrical properties will be constructed. It will be an additional resource that can be used by Gdańsk University of Technology as a part of research and teaching activities.