The poly(methylene blue) (PMB) modified glassy carbon electrode (GCE) exhibiting different electrochemical behavior was prepared via two methods, respectively. The PMB polymer, derived from the two-step electropolymerization, suffered structure conversion between Poly(leuco-MB) and Poly(MB center dot) during cyclic voltammetric measurement and exhibited electrocatalytic activity for reduction of dissolved oxygen (DO). The monodispersed hollow methylene blue doped SiO2 nanoparticles were synthesized in the W/O microemulsion. A new material, PMB doped SiO2 nanocomposites, presenting monolayer sheets with crosslinked cage structure, were electrochemically polymerized on GCE surface. Compared with PMB film, the nanocomposite material provided a significantly improved sensitivity for reduction of DO and an excellent ability to resist interference from macromolecule contaminants. The detection of DO was performed using the nanocomposite material modified electrode. The calibration curve was linear over a DO concentration range of 0.112-5.78 mg L-1 with a correlation coefficient of 0.998 and a detection limit (3 sigma) of 0.037 mg L-1. (C) 2011 Elsevier Ltd. All rights reserved.