In the crystal structure of the title coordination polymer/co-crystal, {[ZnCl(2)(C(18)H(18)N(4))]·C(18)H(18)N(4)}(n), the tetrahedrally coordinated Zn(II) ions are linked by the N-heterocycle into a linear chain. Another N-heterocycle present is not coordinated to the metal atom but inter-acts with the chain through N-H⋯N and N-H⋯Cl hydrogen bonds. The butyl chain of the uncoordinated ligand is disordered over three positions in a 0.511 (4):0.289 (5):0.200 (5) ratio.