The hydrocarbon formation of carbon materials exposed to hydrogen atoms and ions is reviewed. It turns out that surface conditions and modification play a major role in hydrocarbon formation. Graphite exposed to hydrogen plasma exhibits surface properties similar to those of amorphous hydrogenated carbon films and redeposited carbon films. The total chemical erosion yield of these carbon materials is similar for thermal atomic hydrogen and for energetic hydrogen ions, reaching maximum values of ∼0.1 eroded carbon per incoming hydrogen. However, the spectrum of formed hydrocarbons is determined by the energy of the impinging hydrogen. By a thermal H0 exposure, CH3 is formed together with equal amounts of C2Hx and C3Hx. With an energetic H+ bombardment, the main reaction product is CH4 with minor contributions of C2Hx and C3Hx. The amount of C2Hx and C3Hx formation decreases with increasing H+ energy. Hydrocarbon formation at low energies and high flux densities, as in the scrape-off layer (SOL) of fusion devices, is characterized by a broadening of the temperature dependence together with a slight decrease of the absolute erosion yield. Similar results have been obtained by an in situ study of the hydrocarbon formation in the SOL of the Tokamak Experiment for Technology Oriented Research (TEXTOR) plasma using a sniffer probe system.