Very small platinum nanoclusters have been synthesized by reduction of H2PtCl6 center dot 6H(2)O salt with NaBH4 in the presence and absence of water-soluble L-cysteine ligand. The synthesized platinum clusters were supported over anatase titanium dioxide (TiO2) by 1% wt/wt. The spectroscopic properties of Ptr,(L-Cys)m clusters were studied by UV-vis spectroscopy and Fourier transform infrared spectroscopy (FTIR) and its chemical structure were determined by thermogravimetric analysis (TGA) and elemental analysis. The particle sizes of supported and non-supported platinum clusters were characterized by transmission electron microscopy (TEM) and powder X-ray diffraction analysis. As well as their specific surface areas were determined using nitrogen adsorption/desorption measurements, pore volume and average pore diameter were also calculated. Finally, oxidation of styrene is used as a simple model reaction to demonstrate that these systems exhibit the potential to be used as heterogeneous catalysts. The doped monodisperse platinum clusters (1% Ptn(L-Cys)./TiO2) catalyst exhibited the highest catalytic activity and selectivity (100% benzaldehyde) in oxidation of styrene. The non-doped platinum clusters (Pt-n(L-Cys)(m)) showed more catalytic activity than doped polydisperse platinum clusters (1% Pt/TiO2). Hydrogen peroxide was used as oxidizing agent, which exhibited stronger oxidation potential than oxygen gas. The unique atom -packing structure and electronic properties of Ptn(L-Cys)m nanoclusters (-1 nm) are rationalized to be responsible for their extraordinary catalytic activity observed in oxidation of styrene. (C) 2015 Elsevier B.V. All rights reserved.