Layered perovskite-like oxides are solid crystalline substances formed by two-dimensional nanosized perovskite slabs interleaved with cations or cationic structural units. Until present time perovskite-like compounds are actively studied as materials with wide range of important physical and chemical properties such as super-conductivity, colossal magnetoresistance, ferroelectricity, catalytic and photocatalytic activity, thermochemical properties and electrochemical properties. In recent years, there has been a constant interest in using the soft chemistry methods for development of new layered perovskite-like compounds with specified physicochemical properties, as well as design of these materials based on perovskite structure. The present research considers ability of bismuth-containing complex oxide K2,5Bi2,5Ti4O13 to undergo protonation and intercalation of water molecules into interlayer space. The series of derivatives with general formula HxK2,5-xBi2,5Ti4O13*yH2O were obtained in water and nitric acid solutions. The phase transformations during thermolysis processes of obtained derivatives were studied by means of thermogravimetric analysis, simultaneous thermal analysis, thermo XRD and IR spectrometry. As the result a range of new phases with layered structure was obtained and characterized.