We recently reported studies of O2 etching of individual carbon nanoparticles (NPs) in the temperature (TNP) range from 1200 to 2400 K, with several unexpected results. O2 reaction with graphite in this temperature range proceeds by O2 dissociative adsorption at undercoordinated carbon sites ("-C * "), at exposed basal plane edges and defects, creating oxidized surface sites ("-C(O)") that can decay by desorption of oxygen, resulting in no net reaction, or by CO/CO2 desorption, etching the surface. The mechanisms are not as well established for other forms of carbon, but almost certainly involve O2 dissociative adsorption at under-coordinated sites, followed by desorption of oxygen or COx. Graphite, graphene, graphene oxide, carbon black, and diamond NPs all were found to have initial reactivities in the same order of magnitude, with significant NP-to-NP variation attributed to differences in the NP structures and surface site distributions. The initial reactivity for graphitic and carbon black NPs was high and roughly TNP independent below ~1600 K, then fell gradually at higher TNP.