The efficient and selective capture of toxic oxo-anions is highly desirable for environmental retrieval and hazardous waste disposal. This has remained an important task and gained considerable scientific attention due to their harmful effects on the ecosystem and human health. Herein, a porous cationic metal-organic framework (MOF), namely, [CuCl(L)(HO)]·Cl·4DMA·8HO (1), was synthesized (HL = 1,4,8,11-tetrazacyclotetradecane-N,N',N'',N'''-tetramethylenecinnamic acid and DMA = N,N'-dimethylacetamide). 1 shows high stability in aqueous solution and represents an extraordinary example that is capable of efficiently capturing environmentally toxic CrO and MnO anions. Moreover, the removal of CrO and MnO anions from water was also explored in the presence of other competing anions.