A water molecule can be bonded to a sulfate ion through hydrogen bonding. Hydrogen bonding is a type of non-covalent bond that occurs when a hydrogen atom covalently bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) interacts with another electronegative atom. In the case of a water molecule and a sulfate ion, the hydrogen atoms of the water molecule can form hydrogen bonds with the oxygen atoms of the sulfate ion.

The hydrogen bonding between water molecules and sulfate ions can have important implications for the structure and properties of materials. For example, in the mineral gypsum (CaSO4·2H2O), water molecules are hydrogen bonded to the sulfate ions, which helps to hold the crystal structure together. In addition, hydrogen bonding between water molecules and sulfate ions can affect the solubility of sulfate salts in water.