The stabilities of tris‐oxalato complexes of trivalent metals like Fe, Cr, Al, Ga have been studied. These compounds have been found to decompose in steps by interaction with acids. The stepwise instability constants and also the overall instability constants of the reactions MOx3‴ → MOx′2 + Ox″, MOx′2 → MOx+ + Ox″, MOx+ → M3+ + Ox″ and MOx3‴ → M3+ + 3 Ox″ have been measured. Copyright © 1957 Verlag GmbH & Co. KGaA, Weinheim