The simultaneous synthesis of gold nanoparticles in both water and chloroform by the spontaneous reduction of aqueous chloroaurate ions by a diamine-containing oxyethylene linkage that partitions in both phases is demonstrated. The oxidation of the diamine consequent to reduction of the gold ions results in the polymerization of the diamine and formation of a polymeric coating around the gold nanoparticles. The gold nanoparticles are uniform in size ranging between 3 and 6 nm. The nanoparticles capped with the polymer may be stored as a powder and readily redispersed in nonpolar organic solvents and water, indicating that the surface of the polymer capping the nanoparticles is significantly different in both cases.