By ion echange analysis, dialysis and electrophoresis of double labelled (32P and 51Cr) chromic β-glycerophosphate complexes, the stability of the bond β-glycerophosphate-chromium under different conditions of olation and oxolation has been studied. The glycerophosphate can form complexes with 1 or 2 moles per chromium atom. Below pH 6.0 the complexes present cationic characteristics, while between pH 6.0 and pH 8.0 they behave as anions. The oxolation provokes a release of β-glycerophosphate from the complex. The physicochemical characteristics of these complexes are reflected in their behaviour “in vivo” when injected into mice.