A cyanide-bridged decanuclear [Co6Fe4] cluster was synthesized by a one-pot reaction, and the magnetic properties and electronic configuration were investigated. The complex displayed thermally controlled electron-transfer-coupled spin transition (ETCST) behavior between Cow(III) low-spin-NC-Fen low-spin and Co-II high-spin-NC-Fe-III low-spin states, as confirmed by single-crystal X-ray, magnetic, and Mossbauer analyses.