Abstract: The process serves for preparing sodium ion-free X carbonate or hydrogencarbonate effervescent powder, such granules or such tablets. The active substances X, at least calcium carbonate, moistened with a small amount of alcohol and water, are mixed as powder with a small amount of lactobionic acid in a partial vacuum in a vacuum tank with continual pumping. As a result, the calcium salt (CaCO3) of the calcium in the surface layer of the powder particles reacts with the lactobionic acid, effervesces and releases a small amount of CO2. Consequently, the pressure in the vacuum tank rises and after the end of the effervescent reaction the internal pressure in the vacuum tank drops back to the starting value through the continual pumping. In so doing, the powder dries. After removal from the vacuum chamber an acid, preferably citric acid, as an effervescing agent is added, and subsequently the powder is electively pressed into tablets.