Carbon nanospheres (O similar to 50 nm) prepared by chemical vapor deposition exhibit Curie-type paramagnetism, with a localized spin density N-s = 4.01 x 10(19) spins/g. The spheres are solid, as shown by their cross-sections. Their low surface area excludes the presence of exposed graphene layers at the surface being the origin of paramagnetic centers. Inside the carbon spheres, HRTEM reveals a concentric wavy pattern of graphitic (sp(2)-bonded) clusters (size < 2 nm) embedded in disordered carbon. The high density of carbon atoms with sp(2)-spa(3) hybrid orbitals acting as paramagnetic centers, at interfaces between graphitic (sp(2)-bonded carbon) clusters and amorphous carbon, can explain the magnetic measurements. (C) 2007 Elsevier B.V. All rights reserved.