In this work, a new hydrogen peroxide (H 2 O 2 ) sensor was reported based on electropolymerizing pyrocatechol violet (PCV) on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNTs). The modified electrode was characterized by cyclic voltammetry (CV) and scanning electron micrography. The result of electrochemical experiments showed a favorable catalytic activity toward the reduction of H 2 O 2 at À0.4 V with a linear response range from 2.0 lM to 2.4 mM and a detection limit of 0.7 lM (at a S/N ¼ 3). The well catalytic activity of proposed sensor could be attributed to the poly-PCV/MWCNTs composite film on the electrocatalytic reduction of H 2 O 2 . In addition, the sensor also exhibited a high sensitivity, good stability, and reproducibility.