A method of coating hydroxylated surfaces by gas phase grafting is described. Especially acyl groups, silyl groups and/or alkyl groups are located on the surface of materials by gas phase grafting. The grafting method is a dry process. The material to coat can be organic or inorganic materials. The produced surface coated material are strong and durable and material normally not water-proof can be water-proof due to the surface treating. Examples of items produced from surface treated material may be water-proof cardboard boxes, other containers, furniture, interior for cars and boats. Items produced from organic materials such as from plant parts are biodegradable.