The title complex, [Cd2Cl4(C13H17N3)2]·H2O, is centrosymmetic and contains two Cd(2+) ions bridged by two Cl(-) ions, leading to a strictly planar Cd2Cl2 core. Each Cd(2+) ion is further coordinated by an additional Cl(-) ion and three N atoms of a tridentate 8-[2-(di-methyl-amino)-ethyl-amino]-quinoline ligand in the form of a considerably distorted octa-hedron for the overall coordination sphere. A lattice water mol-ecule is located on a twofold rotation axis and links pairs of complexes through N-H⋯O and O-H⋯Cl hydrogen bonds.