A 1R,2R-diaminocyclohexaneplatinum(II) complex of B2O5H2(2-), (C6H14N2)Pt(B2O5H2).2H2O, is synthesized by reacting (C6H14N2)Pt(OH)2 with boric acid in the presence of dipotassium tetraborate tetrahydrate in aqueous solution. X-ray structural analysis revealed that the B2O5H2(2-) anion and the platinum(II) cation form a six-membered chelate.