Abstract: Sodium amoxycillin, of use for example by parenteral administration, is prepared by:(a) suspending amoxycillin trihydrate in a mixture comprising an aprotic organic solvent and a lower alcohol;(b) solubilizing the amoxycillin trihydrate by the addition of a low molecular weight amine of the group of cyclic or heterocyclic aliphatics;(c) adding to such solution the sodium salt of diethyloxalacetic acid, agitating the reaction mixture at a temperature of from -10.degree. C. to ambient temperature and finally isolating the sodium amoxycillin by filtration after its precipitation in the reaction medium by the addition of an aprotic organic solvent.