In this study, an aromatic sulfonic dye, Calmagite (Calm) was electropolymerized on a pencil graphite electrode (Poly-Calm/PGE) to investigate the electrocatalytic oxidation and flow injection (FI) amperometric detection of NADH. Cyclic voltammetric studies show that Poly-Calm/PGE exhibits a high electrocatalytic activity towards the oxidation of NADH. Then, determination of NADH was performed at Poly-Calm/PGE using FI-amperometric technique with a homemade flow cell which was fabricated for PGEs. FI-amperometric measurements showed that linear response of NADH was found between 0.10 and 100.0 mu M. Detection limit was found as 0.03 mu M (based on 3 S-b/m) at Poly-Calm/PGE. This study is the first one for FI-amperometric analysis of NADH using Poly-Calm/PGE which provides a simple, low cost, and sensitive determination of NADH. The proposed sensor can be a good alternative method for determination of NADH and construction of a biosensor based on dehydrogenase enzyme in future.