The well-defined titania nanotube arrays with a tunable pore size and tube length have been fabricated in an organic medium-assisted anodization process. The obtained titania nanotubes have been applied for electric double layer capacitor applications. The electrochemical capacitance performance is highly dependent on the pore size and tube length of nanotube arrays. The increase of pore size can significantly enhance specific capacitance of titania nanotube arrays. Comparatively, the increase of tube length can only improve specific capacitance to a small degree. In addition, a higher specific capacitance of titania nanotube array can be achieved in an acidic solution rather than an alkali solution.