In this study, we report the synthesis and characterization of a new rhodium(II) succinate complex (Rh2(suc)4) and its immobilization on lauric acid bilayer-coated maghemite nanoparticles (MGH-2L/Rh2(suc)4) and subsequent adsorption with bovine serum albumin (MGH-2L/Rh2(suc)4/BSA). Rh2(suc)4 has been characterized by elemental analysis, potentiometric titration, TGA, MS, FTIR and UV-Vis analysis. The maghemite phase was confirmed by XRD, and a diameter of 10 nm was obtained by Sherrer equation. The VSM experiment showed superparamagnetic properties. TEM showed nanoparticles with a spherical shape and a mean diameter of 8.5±0.4 and 9.1 ± 0.4 nm for MGH-2L/Rh2(suc)4 and MGH-2L/Rh2(suc)4/BSA, respectively. FTIR and TGA confirmed the immobilization of Rh2(suc)4 and bovine serum albumin adsorption on superparamagnetic iron oxide. Hydrodynamic size (DH) and zeta potential (ζ) measurements were made in aqueous, NaCl and DMEM media. DH for dispersions was lower in aqueous medium, but increased in saline and DMEM media. In aqueous and saline media, ζ was not altered for MGH-2L and MGH-2L/Rh2(suc)4, but was significantly lower for MGH-2L/Rh2(suc)4/BSA. Therefore, MGH-2L/Rh2(suc)4/BSA was the most stable dispersion, meaning that BSA coating prevents aggregation more than lauric acid bilayer coating. MGH-2L/Rh2(suc)4 and MGH-2L/Rh2(suc)4/BSA dispersions induced cytotoxicity in breast carcinoma (MCF-7) and fibroblast cells in culture, and this effect was higher than that exerted by free Rh2(suc)4 and more specific to breast carcinoma cells than to fibroblasts. Therefore, we suggest that these dispersions have an important potential for future clinical applications and, thus, they should be considered a platform to enhance Rh2(suc)4 cytotoxicity, specifically in breast carcinoma.