Metallic nanoparticles have been intensively studied for optical, thermoelectric, and catalytic applications during the past decade. Platinum nanoparticles, in particular, have been shown to exhibit different catalytic activities for various shapes. This may lead to improved selectivity for chemical reactions due to the differing surface properties of each shape. Nanoparticles have been synthesized in the solution phase by using surface capping agents such as low molecular weight ligands, polymers, or amphiphilic surfactants in order to stabilize higher surface energy facets. The majority of platinum nanoparticle shape control has been achieved using foreign metal ions such as Ag or Fe. Selective adsorption of these metal ions on the particle surfaces can enhance the growth rate along different directions (e.g. [100] vs [111]) to give different shapes with defined crystallographic orientations. However, these foreign metal ions may block catalytically active sites resulting in a significant decrease in reactivity. Therefore, new methods for the synthesis of shape-controlled platinum nanoparticles without the inclusion of foreign metal ions are highly needed for catalytic applications. In this study, cubic, cuboctahedral, and porous platinum nanoparticles were synthesized using a charged surfactant as a capping agent. Compared to polymeric capping agents, charged surfactant molecules allow for greater access to active sites providing a higher activity for catalytic reactions. Synthesis of different shapes has been achieved by controlling a reduction method without aid of foreign metal ions. Potassium tetrachloroplatinate and myristyltrimethylammonium bromide (C14TABr) were combined to form metallo-micelles as the precursor for platinum nanoparticle formation. Subsequent reduction of the metallo-micelles by ascorbic acid yielded porous dendritic particles. On the other hand, reduction by sodium borohydride promoted the growth of cubes or cuboctahedra.The cuboctahedra with mixture of [100] and [111] surfaces were formed at a higher reducing rate, and cubes bound by only [100] surfaces dominated at a lower rate of recution. Catalytic activity of the nanoparticles was tested for ethylene hydrogenation. The activation energy was measured as 7.5 ~ 9.6 kcal/mol for cubic, cuboctahedra, and porous particles. The nanoparticles synthesized in this study exhibited a much higher catalytic activity than nanoparticles prepared with polyvinylpyrrolidone and Ag. Assembly of the nanoparticles to form dense 2D arrays was studied by the Langmuir-Blodgett technique. We also investigated the effect of the surface chemical environment on assembly by exchanging the C14TABr with alkylthiol molecules.