A method of deacidifying paper wherein the paper has a substantially cellulose fiber base or substrate by exposing the paper to the vapors of a volatile organometallic compound and subsequently decomposing said compound to a base or alkaline material in situ. The treated material is usually first dried in vacuo and exposed under anhydrous or nearly anhydrous conditions to the organic-metallic compound. The method has the advantage of being able to treat large quantities of material at any one time. -- CCI