Selective oxidation of H2S into elemental sulfur at near-ambient temperature have been carried out over NiS2, nanoparticles encapsulated inside multi-walled carbon nanotubes (MWNTs). The high capacity of solid sulfur storage on the MWNT-based catalyst compared to that of macroscopic SiC grains was thus attributed to the large void volume outside the MWNTs available for the Sulfur storage when compared to the void volume outside the SiC grains. (C) 2004 Elsevier B.V. All rights reserved.