The generality of the phenomenon of nanocluster formation in different types of solids was shown by the example of complex oxides of 3d elements in the form of nanoparticles and quasi-two-dimensional and three-dimensional ceramics. It was found that the anomalies of the magnetic properties of all systems studied are explained by the presence of nanoclusters of atoms of transition elements. The effect of nanoclusters on the properties of both nanopowders and bulk materials was discussed.