This work reports the synthesis and characterization of palladium(ii) complexes Pd(L1)2 (1), Pd(L2)2 (2), Pd(L3)2 (3) and Pd(L4)2 (4), where L1H: 1-naphthaldehyde thiosemicarbazone; L2H: 4-phenyl-(1-naphthaldehyde)thiosemicarbazone; L3H: (2-hydroxy-1-naphthaldehyde)thiosemicarbazone; L4H: 4-phenyl-1-(2-hydroxy-1-naphthaldehyde)thiosemicarbazone. All four complexes show in vitro antiproliferative activity against the following human tumor cell lines: H460, DU145, MCF-7, M14, HT-29, K562, and HuTu 80. In particular Pd(L1)2 has the most potent activity for all the studied cell lines (IC50 ∼ 1 μM), with the exception of H460. Pd(L2)2 is a promising candidate as a pharmacological agent, since it presents a significant activity and is more innocuous than cisplatin against mouse fibroblast normal cells, 3T3. Pd(L4)2 is the complex which exhibits the lowest activity against the same cell line (IC50 ∼ 11 μM), being ten times lower than that of Pd(L1)2. These complexes were used to functionalize chitosan coated superparamagnetic magnetite nanoparticles with a metallic core of 11-13 nm, and the activity of these functionalized nanoparticles (NPs) against diverse human tumor cell lines was also tested. The nanoparticles functionalized with Pd(L1)2, Pd(L3)2 and Pd(L4)2 show antiproliferative activity against DU-145, while those with Pd(L2)2, Pd(L3)2 and Pd(L4)2 against HuTu80. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2016.