The title Cd II complex, [Cd(S 2 O 3 )(C 10 H 8 N 2 )], consists of polymeric chains running along the monoclinic symmetry axis. The elementary units are defined by pentacoordinated Cd II atoms bonded to three different thiosulfate groups and a bidentate bipyridine ligand. The bridging thiosulfates bind metal centres through two different sequences, Cd1-S1-Cd1' and Cd1-O1'-S2'-S1'-Cd1', thus defining a six-membered ring. Individual chains are held together solely via van der Waals interactions.