Chemical methods for the synthesis of powders of complex oxide systems (mainly with perovskite structure) and solid solutions, ceramics and films based on them. In particular, these are ion-conducting titanates and niobates, ferromagnetic manganites, ferroelectric semiconductors and non-linear materials based on titanium barium, and others. Research methods that provide a tool to predict and understand the interrelation between structural, electrical and physical properties of complex oxides. In particular, there are chemical analysis, infrared spectroscopy, electron paramagnetic resonance, differential thermal analysis, X-ray powder diffractometry (phase analysis and Rietveld full-profile analysis), electron microscopy (including EDX element analysis), research in wide frequency and temperature ranges (in particular, the method of complex impedance).