AbstractThe mechanism of cross‐linking of cellulose by glyoxal has been investigated using various alcohols as models for cellulose. Competitive hemiacetalizations of glyoxal show that vicinal diols are much more reactive than isolated alcohols. With a catalyst, both kinds of alcohols react with the hemiacetals, but the isolated alcohols are the most reactive. The main products of acetalization are mixed dioxane bisacetals. Methyl 4‐O‐methyl‐α‐glucoside, considered as a monomeric unit of cellulose, reacts in the same way. The cross‐linking of cellulose by glyoxal is thought to proceed according to the same pattern. The pathways of cross‐linking in the presence of ethylene glycol and diethylene glycol, currently used as co‐reactants of glyoxa