Disclosed is a process for the production of particles of a cefquinome acid addition salt, preferably cefquinome sulfate particles, by precipitation of cefquinome acid addition salt, preferably the sulfate, from a cefquinome betaine solution, wherein acid, preferably sulfuric acid, is added to the betaine solution. According to the invention the acid, preferably sulfuric acid, is added quickly in a single shot, in a molar excess of 40% to less than 100%. As a result, particles are formed that comprise agglomerates of microscale primary crystalline particles. This enables providing particles of cefquinome acid addition salt, preferably cefquinome sulfate, in particle sizes commensurate with micronized material, but with improved stability.
