A process for the production of a wood body having increased surface hardness, in which an untreated wood body is impregnated with an aqueous solution of A) an impregnating agent consisting of a 1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one modified with a C.sub.1-5-alcohol, a polyol or mixtures thereof, and B) a catalyst from the group consisting of ammonium or metal salts, organic or inorganic acids or mixtures thereof, dried and then hardened at elevated temperature is described.