The electron-transfer process from an H-terminated diamond (001) surface to an acidic water adlayer, leaving an induced p-type doping in the carbon layers, has been studied using first-principal density functional theory (DFT). The effect of various oxygen-containing species adsorbed to the surface (in the form of an OH group and an oxygen atom in both the ether and ketone positions) on the possibility for electron transfer was also investigated. The results show that a perfect H-termination, as well as the presence of one OH group (equivalent to a surface coverage of approximately 8%), will give an electron transfer of 1.76 and 1.89 e, respectively. There will then be a transfer of electrons from the upper diamond valence band to the lowest unoccupied level in the adsorbate. A corresponding percentage of 8 (Oketone) and 17 (Oether) will effectively hinder the electron-transfer process from occurring.