The chemical processes connected with the so-called solid state reaction performed for doping carbon material with alkali metals (alkali metal: lithium) were studied. The as-treated carbon material shows a large reversible mass change during gravimetric measurements performed under hydrogen flow. The mass change, however, is found not to be related to hydrogen storage and release but to adsorption and desorption of water. When heated in the presence of carbon under flowing hydrogen, the alkali salts transform into alkali oxides which are highly hygroscopic. The chemical processes during the solid state reaction are identified by X-ray diffraction analysis, differential scanning calorimetry and mass spectrometry. (C) 2002 Elsevier Science B.V. All rights reserved.