This paper reveals an improved photoelectrochemical activity of single wall carbon nanotube (SWNT) with respect to enhanced photo-induced currents as they are shortened at a few nanometer sizes. Raman spectroscopy, photoelectrochemistry and scanning electronic microscopy (SEM) characteristics indicate a uniform finite-sized SWNT film with distinct physical and photochemical properties. Unlike p-type semiconductive pristine SWNTs, both cathodic photocurrent and anodic photocurrent are observed on shortened SWNT formed thin films. The incident photon conversion efficiency is eight-fold higher compared to the longer SWNTs, suggesting the electronic structure and photoelectrochemical properties of SWNTs are significantly altered by shortening the length of SWNT. The improved photoelectrochemical activities open a new perspective to use finite-sized SWNTs in combination with other semiconducting materials for fabrication of efficient optoelectronic devices, nanotube optical detectors or emitters that can be operated across a wide range of optical wavelengths. (C) 2008 Elsevier Ltd. All rights reserved.