The effects of a Ti buffer layer on structural and electrochemical properties of arrayed nitrogen-containing carbon nanotubes (CNx NTs) directly grown on Si substrates have been investigated. Cyclic voltammograms using Fe(CN)(6)(3-)/Fe(CN)(6)(4-) as redox couple were measured to study the electrochemical activities of CNx NTs. The highest peak current density was achieved at an optimal Ti thickness of 20 nm owing to the good conductivity of TiSi2 and high number density of NTs. Therefore, we have demonstrated the direct growth of aligned NTs on Ti- buffered Si with improved electrochemical activity that is believed to be suitable for advanced microsystem applications. (c) 2006 The Electrochemical Society.