A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single wall carbon nanotubes (SWCNTs) and phenazine derivative of Mn-complex. With immersing the GC/CNTs modified electrode into Mn-complex solution for a short period of time 20–100s, a stable thin layer of the complex was immobilized onto electrode surface. Modified electrode showed a well defined redox couples at wide pH range (1–12). The surface coverages and heterogeneous electron transfer rate constants (k s ) of immobilized Mn-complex were approximately 1.58×10 −10 molecm −2 and 48.84s −1 . The modified electrode showed excellent electrocatalytic activity toward H 2 O 2 reduction. Detection limit, sensitivity, linear concentration range and k cat for H 2 O 2 were, 0.2μM and 692nAμM −1 cm −2 , 1μM to 1.5mM and 7.96(±0.2)×10 3 M −1 s −1 , respectively. Compared to other modified electrodes, this electrode has many advantageous such as remarkable catalytic activity, good reproducibility, simple preparation procedure and long term stability.