from about 10 to 80 u00b0 c more preferably from about 40 to 60 u00b0 c the resulting dispersion is added with a calcium salt for the ion exchange reaction preferred examples of calcium salts are inorganic salts typically cacl 2 ca no 3 2 caso 4 in particular cacl 2 the molar ratio of calcium salt to fosinopril sodium can range from about 0 5 to 1 preferably from about 0 7 to 0 8 fosinopril calcium form i separates from the dispersion and can be recovered with known techniques such as filtration or centrifugation preferably by previous cooling of the resulting suspension at a temperature ranging from about 15 to 20 u00b0 c in order to allow the formation of a more easily filtrabile solid a water miscible anti solvent can be optionally added to the starting aqueous dispersion preferred examples of anti solvents are ketones in particular acetone ethers in particular tetrahydrofuran diethyl ether and dioxane dipolar aprotic solvents in particular acetonitrile and alcohols in particular methanol ethanol and isopropanol the ratio of antisolvent to water in the starting dispersion can range from about 5 to 20 v v preferably from about 10 to 15 v v the resulting product is dried preferably under vacuum the drying temperature of the product depends on the solvent mixture as is known as used in the present description the term u201c about u201d means approximately 10 more or less the novel crystalline form of the invention is mainly useful in the pharmaceutical technique in particular in filtration drying sieving formulation operations etc fosinopril calcium form i of the invention can be.