In this paper, actuation properties of carbon nanotubes are discussed. Samples of freestanding nanotubes on nanostructured metallic blocks have been prepared. Using a conducting AFM tip, electrons can be injected into the nanotubes. As a consequence, the nanotube expands in a similar way as buckypaper does in an electrolyte. From experimental data, the relative length change is estimated to be less than 1%. These findings are taken as a demonstration of an electromechanical actuator based on individual single walled carbon nanotubes. (C) 2002 Elsevier Science B.V. All rights reserved.