Abstract: The present invention relates to granules comprising a ?-lactam antibiotic, wherein CH2S(72h)<50 ?l of H2S gas per kg of ?-lactam antibiotic, wherein CH2S(72h) is the volume of H2S gas above said granules per kg of said ?-lactam antibiotic, when a sample of between 3.5 and 4.5 g of said granules is kept in a closed container having a volume of 20 ml at a temperature of 22° C. during 72 hours at atmospheric pressure (1 bar). The invention also relates to a process for the preparation of granules comprising a ?-lactam antibiotic, said process comprising feeding said ?-lactam antibiotic to a roller compactor to form compacts, size reducing, e.g. milling the compacts to produce granules, wherein the temperature of the ?-lactam antibiotic that is fed to the roller compactor is sufficiently low that CH2S(72h)<50 ?l of H2S gas per kg of ?-lactam antibiotic, wherein CH2S(72h) is the volume of H2S gas above said granules per kg of said ?-lactam antibiotic, when a sample of between 3.5 and 4.