Disulfide bond was cleaved by a catalytic amount of nitric oxide in the presence of oxygen, which was confirmed by experiments employing two symmetrical disulfides. Thp reaction resulted in the formation of unsymmetrical disulfides in nearly 50% yields. The steric hindrance of alkyl disulfide slowed the reaction rate, and an electron-donating group on the aryl disulfide promoted the reaction. The substituent and S-nitrosothiol effects suggested that the reaction was initialized with an oxidative process by NO+.