磷酸氢镁具有如下特征:
Dimagnesium phosphate is a compound with formula MgHPO4. It is a magnesium acid salt of phosphoric acid.It can be formed by reaction of stoichiometric quantities of magnesium oxide with phosphoric acid.MgO + H3PO4 → MgHPO4 + H2O.It is one of the compounds that have E number E343.
微溶于冷水，溶于酸。205 ℃时失去１个结晶水，加热至550～650℃时分解成焦磷酸盐。在磨碎及加热脱水时，虽然有MgHPO4的组成，但得不到晶体，经过非晶体，脱水缩合而成为焦磷酸镁。