A novel method of two-dimensional (2-D) synthesis of anisotropic nanoparticles have been developed in which nanoparticle growth is an example of 2-D process where true 2-D diffusion of precursor molecules and active intermediates, metal atoms and its complexes, nucleus and growing nanoparticles, surfactants and additives occurs only in the plain of a monolayer at the gas/liquid interface. Nanoparticles were generated via ultraviolet decomposition of a volatile insoluble metal-organic precursor compound (iron pentacarbonyl) and by chemical reduction of palladium from Pd3(CH3COO)6 molecules in a mixed Langmuir monolayer with stearic acid, arachidic acid or octadecyl amine on the aqueous subphase surface. The properties of such surfactants to form Langmuir monolayer and to prevent aggregation of nanoparticles were here combined successfully. Atomic force microscopy, scanning tunneling microscopy and transmission electron microscopy techniques were used to study morphology of deposited nanoparticulate monolayers. The size and shape of nanoparticles were dependent substantially on the monolayer composition and state during the synthesis process. We demonstrate that planar synthesis in a monolayer at the gas/liquid interface allows to produce anisotropic extremely flat nanoparticles with very high surface to volume ratio and unique morphologies such as iron-containing magnetic nano-rings.