The production of methane on carbon (papyex) surfaces under sub‐eV atomic hydrogen bombardment has been measured in an ultrahigh vacuum system subjected to special cleaning procedures. These results and previously published methane yield results are compared and their applicability to fusion technology is assessed. A critical analysis of the available data leads to the following conclusions: (i) The inconsistent methane yields spanning four orders of magnitude are most likely due to different experimental procedures. (ii) The monotonically decreasing methane yield as a function of sample temperature, obtained by some groups, is most probably due to the fact that deactivated surfaces were exposed to hydrogen bombardment. (iii) The methane yields which present a maximum at a certain temperature in the range 700–850 K resulted from bombardment of activated surfaces; and (iv) the shift in temperature at which the methane yield maximum occurs in the different studies may be due to temperature nonuniformities over the exposed surfaces and/or different states of activation.