We show that carbon nanotubes (CNTs) accelerate the wet etching of silicon dioxide in a strong alkaline solution. This catalytic effect is due to the spontaneous adsorption of hydroxide on the surface of the CNTs. Such adsorption creates an electrical double Layer around the CNTs within which the concentration of hydroxide is higher than the bulk value. Our result suggests that the electrical double Layer can be used to pattern nanoscale features, Fabrication of SiO2 trenches with similar to 60 nm lateral resolution is demonstrated.