Detonation-prepared nanocrystalline diamond powders usually contain hydrogen. Herein, the synthesis of practically hydrogen-free nanodiamond particles by detonation of benzotrifuroxan (BTF) and their comprehensive characterization by elemental analysis, X-ray diffraction, electron microscopy, DSC/TGA, and BTE specific-surface determination is described. The effects of the porosity of BTF and of various neutral or carbonic admixtures to the explosive on the reaction thermodynamics as well as the yield and properties of the product were explored theoretically and experimentally. Hydrogen contamination of nanodiamond was investigated using solid-state NMR spectroscopy and possible sources of hydrogen explored. Admixing hygroscopic solids to the explosive introduced 0.1 to 0.6% of hydrogen, as did purification in acidic (rather than neutral) media.