The mefenamic acid sodium, potassium, and calcium salts with general formulae [Na (mef)(H2O) 2] n· nH2O,[K (mef)(H2O)] n and [Ca (mef) 2 (H2O) 2] n· nH2O have been synthesised, studied by X-ray crystallography, 1H and 13C NMR and IR spectroscopy. The complex salts are air stable and soluble in water. During heating the Na and K complexes melt in the complexed water and next recrystallise in anhydrous form. In the solid state all ...