Abstract: Preparation process of 2-chloro pyrimidine from 2-amino pyrimidine, hydrochloric acid and an alkali metal nitrite, the reagents being in substantially similar proportions as in the previously known methods, consisting in preparing a mixture of hydrochloric acid and of a non polar solvent of low boiling point, then adding 2-amino pyrimidine wherein there is slowly added, at room temperature, the chloride of a metal selected from the group consisting of the transition metals, tin, antimony, thallium and zinc, then introduced, under an inert gas circulation, the selected nitrite at a temperature not exceeding 10.degree. C. and finally poured the reaction mixture in iced water.