The present paper covers the investigation and application of dual carbon fiber microelectrodes. The electrodes were characterized by cyclic voltammetry and chronoamperometry resp. The steady state current equation of dual parallel microelectrodes is verified experimental and the deviation between the theoretic curve and the experimental was discussed. Furthermore, vitamin B1 was detected indirectly in generator-collector mode at the electrodes. Satisfactory results were obtained with detection limit of 1.0 ?10-6 mol . dm-3 and the linear calibration graph range over 7.5 ?10-4 to 7.5 ?10-6 mol . dm-3 of vitamin B1.

Key words: VITAMIN B1, SENSORS, ELECTROCHEMICAL ANALYSIS, CARBON FIBERS, MICROELECTRODE, CYCLOVOLTAMGRAPH