A novel method for preparation of stable emulsions of slightly water soluble compounds is described. The method implies that the slightly water soluble compound diffuses through water and becomes absorbed into polymer particles which in a previous step have been brought to absorb a water insoluble, relatively low molecular weight compound. By this two step swelling process the polymer particles can be brought to absorb more than 100 times their own volume of the low molecular weight compounds to form stable o/w emulsions of the latter, with high oil content, and with a droplet size and size distribution which is completely determined by the size of the polymer particles in the latex applied initially. Monodisperse emulsions with large droplet size could easily be prepared. When the slightly water soluble compound added in the second step is a vinyl monomer which may subsequently be polymerized, the method represents a seed technique which is especially favourable for preparation of latexes with large particles size, including monodisperse latexes, with high solid content.