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Four lithium 2‐R‐hydroquinolinide complexes [1‐(2‐(R)‐C9H7)NLi·THF2]2 (1 R = Me, 2 R = nBu) and [1‐(8‐(Me)‐2‐(Bun)‐C9H6)NLi·X]2 (3 X = THF, 4 X = Et2O) were prepared by the nucleophilic addition reaction of quinoline and 8‐methylquinoline with MeLi or BunLi, respectively. All complexes have been characterized through NMR spectroscopy. Complexes 2–4 were determined by X‐ray crystallography. Interestingly, Li atom in 1 and 2 is tetracoordinate, whereas Li atom in 3 and 4 is three‐coordinate. All these complexes showed super‐high activity for the ring‐opening polymerization (ROP) of ε‐caprolactone in both the absence and presence of BnOH at 35 °C in CH2Cl2. By the 1–4 catalytic systems with or without BnOH as a co‐initiator, the ROP of ε‐CL proceeded well in a living manner as evidenced by the predictable molecular weights, narrow molecular weight distributions, and kinetic studies. MALDI‐TOF MS analysis revealed that the resultant PCL showed a cyclic structure in the absence of BnOH and a BnO– capped linear structure was observed in the presence of BnOH. [ABSTRACT FROM AUTHOR]