An inorganic polymer [CuPtCl 6·CuPtCl 4] n , using CuPtCl 6 as the precursor monomer, was electrodeposited onto a carbon fiber ultramicroelectrode. The modifier film displays excellent electrocatalytic activity for the oxidation of NO at ∼700 mV (vs . SCE). The modified electrode was prepared by continuous cyclic scanning between 700 and −800 mV in a solution containing CuCl 2 and K 2PtCl 6. A Nafion membrane coating was used to avoid the interference of nitrite. The effect of film thickness, pH, and the interfering species to NO detection have been studied. With differential pulse voltammetry, the linear response range is from 1 × 10 −7 M to 2 × 10 −4 M with a sensitivity of 19.7 ± 0.6 μA cm −2 μM −1. With amperometry, the linear range of detection is from 1 × 10 −8 M to 2 × 10 −4 M with a detection limit of 5 nM (signal : noise = 3). An electrochemical sensor for the detection of biological NO is described based on this modification of a 5 μm tip-sharp carbon fiber electrode. The application of this sensor in the detection of biological NO was demonstrated by measuring ATP-stimulated NO release from freshly dissected chicken cochlea neuron cells.