Abstract: Sheets or moulded bodies, for example particle board, are manufactured by hot pressing a lignocellulosic material in contact with an organic polyisocyanate and a wax release agent which is a vegetable wax, a modified vegetable oil, a microcrystalline wax or a mineral wax, said wax release agent having a melting point of at least 70.degree. C. Preferably the wax release agent is applied to the lignocellulosic material in the form of a dispersion in an aqueous emulsion of the polyisocyanate. The process facilitates the release of the sheets or moulded bodies from the caul plates or platens of the press.