This paper presents the results of investigations on the possibility of using protic ionic liquids as a hardener and modifier of melamine-urea-formaldehyde (MUF) adhesive resins. In research dialkylmethylammonium dodecylbenzenesulfonate base protic ionic liquids with varied amounts of carbon in alkyl group were used. The plywood manufactured using protic ionic liquids and MUF resin was characterized by a complete water resistance of glue lines, thus meeting the requirements of EN-314-02 standard.