A process for producing a coating material composition characterized by reacting an emulsion of a polymer having an acid value of 20 to 200, prepared by polymerizing an ethylenically unsaturated monomer, with a calcium compound in a chemical eqivalent of 0.05 to 0.9 based on the above acid value. Usable calcium compounds include oxide, hydroxide and carbonate thereof and may be reacted with the polymer after the pH of the emulsion is regulated to 4.5 to 9 by adding a base thereto. The composition is stable for long and does not cause environmental pollution because it does not contain heavy metals. Because no metallic complex is used therein, it is free from disagreeable odor due to ammonia generated by complex decomposition during drying after coating.