The present invention relates to a product of amoxicillin trihydrate, having a free water content of less than 0.1 wt.%, preferably less than 0.07 wt.%, more preferably less than 0.05 wt.%, measured at an equilibrium relative humidity of 30% and at a temperature of 25 DEG C. The product is advantageously used in mixture with clavulanic acid. The invention also relates to a process for the preparation of the new product.