A unique feature of nanoscale carbon materials is the nature of their surfaces and how their surfaces interact with other species. The carbon materials specifically studied here include single-wall carbon nanotubes, nanoscale carbon nitrides, and a brief study of nanodiamonds from meteorite carbon, and related diamond surface chemistry. These nanometer sized carbon materials often possess curved surfaces. These curved surfaces can result in special structure-property relationships, such as a unique resistance to oxidation in the case of the nanotubes. Also the synthesis of nanoscale structures can be governed by surface interactions with the growth substrate, as shall be demonstrated with the carbon nitrides. The final materials obtained after such chemical treatments, should prove useful in applications such as catalysis, gas storage, chromatography, molecular electronics, high-strength composites, batteries and fuel cells, and abrasives.