A tumor-inhibiting platinum (II) oxalate complex and its use as a therapeutic agent are provided, in particular as a tumor-inhibiting medicament. The complex may be compounds of the general formula (I), wherein the substituents R1, R1′, R2, R2′, R3, R3′, R4, and R4′ are independently selected from the group consisting of hydrogen, unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cycloalkyl, unsubstituted or substituted cycloalkenyl, unsubstituted or substituted aryl and unsubstituted or substituted alkylaryl radicals, the substituents R5, R5′, R6, and R6′ are independently selected from the group consisting of hydrogen, unsubstituted or substituted alkyl, and unsubstituted or substituted alkenyl radicals, and wherein optionally in each case at least two of the substituents R1, R1′, R2, R2′, R3, R3′, R4, and R4′ can form with one another at least one unsubstituted or substituted alkylene, unsubstituted or substituted alkenylene radical or an unsubstituted or substituted aromatic ring, and wherein optionally at least one of the carbon atoms of the cyclohexane ring bearing the substituents R1, R1′, R2, R2′, R3, R3′, R4, and R4′ is replaced by a heteroatom, and if the heteroatom is oxygen, the substituents R1, R1′, R2, R2′, R3, R3′, R4, and R4′ can additionally be hydroxy radicals, and pharmaceutically compatible salts of them, provided that at least one of the substituents R1, R1′, R2, R2′, R3, R3′, R4, or R4′ is not equal to hydrogen and the substituents R1 or R1′ and R4 or R4′ do not form any unsubstituted C1-2-alkylene radical with one another.