Two lantern-shaped, high-nuclearity 3d-4f clusters {Ln52Ni52}(Ln = Gd and Dy) were synthesized by using iminodiacetic acid (H2IDA) and isonicotinic acid (HIN) as the co-ligand under solvothermal conditions. Magnetic studies show a large magnetocaloric effect (MCE) for the gadolinium analogue.