This oral communication will present new data on the electrocatalytic activity and stability of Pt nanoparticles of different size (3-10 nm) and shape (cubic, octahedral/tetrahedral or mixed) synthesized by a modified polyol-based. The statistic partition among different single crystal surface planes of the particles was characterized using high-resolution TEM pictures and irreversible Bi and Ge adsorption. The electrocatalytic activities of the particles were monitored by electrochemical CO stripping and methanol electro-oxidation. Clear and sensitive shape and size dependences of the CO stripping peak potential and the methanol electro-oxidation peak current were observed. Additionally, the stability of these particles after being subject to multiple (~ 200) CV cycling was investigated using both TEM and electrochemical methods. It was observed that octahedral/tetrahedral particles preserved their shapes the most during electrocatalysis.