Monodisperse spherical FeCo nanoparticles were synthesized by reduction decomposition of Fe(acac)(3) and Co(acac)(2) in the presence of surfactants and 1,2-hexadecanediol. The particle size can be controlled by varying the surfactants. The presence of surfactants on the surface of the nanocrystal protects them from surface oxidation. The saturation magnetization of as-synthesized particles is found to be size dependent. The as-synthesized FeCo nanoparticles can be made air-stable by annealing at 500 degrees C for 30 min without causing particles sintering.