Carbon-encapsulated Fe3C nanoparticles with diameter of about 10 nm were synthesized on a large scale via co-carbonization of durene and ferrocene at 540 degreesC tinder autogeneous pressure. TEM and HREM examinations confirmed that the carbon-encapsulated Fe3C nanoparticles were uniformly dispersed in carbon matrix and the Fe3C nanoparticles were surrounded by several carbon layers with well ordered arrangement. The formation mechanism of carbon-encapsulated Fe3C nanoparticles was discussed briefly. This novel and simple approach constituted a more practical method to prepare encapsulated nanoparticles than the present ones. (C) 2003 Elsevier Science B.V. All rights reserved.