Ultrasonic spray pyrolysis (USP) method has been used to prepare metallic and ceramic materials in the form of aggregates consisting of nanocrystals and/or amorphous phase. The technique allows the use of a wide range of precursors and can be used to prepare fine hollow spherical particles with very thin (< 10 nm) walls. As far as morphology is concerned, the synthesized powders satisfy the requirements for precursors for subsequent preparation of new nanostructured thermoelectric materials.