Electrochemical techniques are the most reliable techniques for determination of neurotransmitters and selective determination is their most challenging issue. Herein we have optimized the condition for oxidation of adrenaline and noradrenaline, as the most similar neurotransmitters, to find a simple and fast technique for their selective determination. Under mild acidic condition, oxidation of adrenaline is followed by a cyclization reaction and oxidation of the product (ECE mechanism) whereas noradrenaline undergoes just oxidation (E mechanism). The redox potential of the product of ECE mechanism has 350 mV difference with the product of E mechanism. This different in reactivity and redox potential yields two baseline separated reduction peaks for the oxidation products of adrenaline and noradrenaline, which used for their selective determination.