PURPOSE: To provide a method for preparing a blocked polyisocyanate without requiring a considerable amt. of a solvent or elevated temp. for dispersing a polyisocyanate into water.

CONSTITUTION: A method for preparation of an aqueous dispersion of a blocked polyisocyanate by reacting an aqueously dispersed polyisocyanate having an isocyanate content of at least 12 wt.% based on the wt. of the polyisocyanate, with a monofunctional blocking agent which is more reactive with isocyanate groups than water at an equivalent ratio of monofunctional blocking groups to isocyanate groups of 0.5:1 to 2:1, is provided. In addition, compositions contg. the aqueously dispersed blocked polyisocyanate prepd. by this method and an isocyanate reactive compd. are provided.