Abstract The influence of fullerene (C60 ) nanoparticles on the cytotoxicity of a highly reactive free radical nitric oxide (NO) was investigated. Fullerene nanoparticles were prepared by mechanochemically assisted complexation with anionic surfactant sodium dodecyl sulfate, macrocyclic oligosaccharide γ-cyclodextrin or the copolymer ethylene vinyl acetate–ethylene vinyl versatate. C60 nanoparticles were characterized by UV–vis and atomic force microscopy. While readily internalized by mouse L929 fibroblasts, C60 nanoparticles were not cytotoxic. Moreover, they partially protected L929 cells from the cytotoxic effect of NO-releasing compounds sodium nitroprusside (SNP), S-nitroso- N -acetylpenicillamine (SNAP), S-nitrosoglutathione (GSNO) and 3-morpholino-sydnonimine (SIN-1). C60 nanoparticles reduced SNP-induced apoptotic cell death by preventing mitochondrial depolarization, caspase activation, cell membrane phosphatidylserine exposure and DNA fragmentation. The protective action of C60 nanoparticles was not exerted via direct interaction with NO, but through neutralization of mitochondria-produced superoxide radical in NO-treated cells, as demonstrated by using different redox-sensitive reporter fluorochromes. These data suggest that C60 complexes with appropriate host molecules might be plausible candidates for preventing NO-mediated cell injury in inflammatory/autoimmune disorders.