Abstract: The present invention relates to an improvement in the recovery of boron values from a mixture of alkali metal borate and alkali metal hydroxide representing discharged fuel from a hydrogen generator apparatus. The mixture is reacted with carbon dioxide and a lower alcohol to form trialkyl borate, alkali bicarbonate and water. A porous water-absorbing material is added to the reaction mixture to absorb water as it forms thereby improving the yield of trialkyl borate. The trialkyl borate is converted to alkali borohydride that is used in the fuel.