Nonoxide SiCN hollow nanospheres were prepared from a block-copolymer comprising of a precursor block and a sacrificial block. The copolymer was first synthesized and then self-assembled into core-shell structured micelles with the sacrificial block forming the core and the precursor block forming the shell. The micelles were subsequently pyrolyzed at high temperatures to transform the shell into ceramics and to completely decompose the core to form a hole. The technique is probably applicable to other material systems.