A unique chiral three-dimensional magnet with an overall racemic double-interpenetrated (10,3)-a structure of the formula [(S)-(1-PhEt)-Me3N](4)[Mn4Cu6(Et(2)pma)(12)] (DMSO)(3)]center dot 3DMS center dot 5H(2)O (1; Et(2)pma = N-2,6-diethylphenyloxamate) has been synthesized by the self-assembly of a mononuclear copper(II) complex acting as a metalloligand toward Mn-II ions in the presence of a chiral cationic auxiliary, constituting the first oxamato-based chiral coordination polymer exhibiting long-range magnetic ordering.