In this study, carbon materials syntheses using a dielectric barrier discharge (DBD) microplasma in supercritical carbon dioxide (scCO(2)) environments are reported. The dependencies of the carbon materials synthesis processing on the environmental temperature, environmental pressure and power frequency were investigated. In contrast to atmospheric-pressure CO, environments, in which no carbon materials could be fabricated, it was possible to fabricate various carbon materials, such as amorphous carbon, graphite and nanostructured carbon materials, using scCO(2) as a processing medium and a raw starting material. In particular, in the vicinity of the critical point of CO2, the quantity of carbon nanostructured materials, such as carbon nanotubes and carbon nanohorns, was larger than under other scCO(2) conditions. It is supposed that the high density and molecular clustering caused by supercritical conditions may affect the formation of such carbon nanostructured materials. In addition, we found that by varying the power frequency, the form of the synthesized carbon materials could be changed. (C) 2006 Elsevier B.V. All rights reserved.