Two hexanuclear 3d-4f cluster complexes containing the pyridine-2-aldoximate ligand (pao−), [Ni2Ln4 (hfac)8(pao)6(CH3COO)2(MeOH)]·H2O·MeOH (Ln = Gd, 1; Ln = Dy, 2; hfac- = hexafluoroacetylacetonate), have been synthesized, which show similar structures with an interesting ‘trigonal bipyramid’ metal topology. Magnetic determinations revealed that the Ni-Gd specie has a spin ground state of 16 due to the dominant ferromagnetic exchange, exhibiting an enhanced magnetocaloric effect, which can be used as the cryogenic magnetic cooler; while the Ni-Dy analogue displays slow magnetic relaxation, typical characteristic for a single-molecule magnet.