This invention is directed to a process for the preparation of a crosslinker composition, comprising the steps of providing a mixture of an aliphatic alcohol A having at least one hydroxyl group and from 1 to 10 carbon atoms, with at least one multifunctional aldehyde C having at least two aldehyde groups —CHO to form a mixture AC, heating the mixture AC to convert at least a part of the multifunctional aldehyde C to its hemiacetal or to its acetal to form a mixture (AC)′, adding to the mixture (AC)′ least one cyclic urea U or the educts to produce the said cyclic urea U in situ, which cyclic urea U has at least one unsubstituted >NH group, and reacting the mixture thus obtained to form a chemical bond between the nitrogen atom of the at least one unsubstituted >NH group of the at least one cyclic urea U5 and the carbon atom of the least one aldehyde group —CHO of the multifunctional aldehyde C, and coating compositions comprising the said crosslinker composition.