Dispersion of double-walled carbon nanotubes (DWCNTs) in ethylene glycol (EG) medium by a simple ultrasonication method is investigated. Excellent dispersion of DWCNTs in EG without addition of a surfactant is found. Surface structure and crystallinity of the DWCNTs undergo little change. The dispersion state of DWCNTs is found to be very important for deposition of Pt nanoparticles on them. The Pt particles prepared in the homogenous dispersion system has a small size and uniform distribution. As a result, the electrochemical activity of the Pt catalyst is much higher than that prepared in the nondispersible system. In terms of the good dispersion in EG medium achieved by a simple method, the DWCNT solutions could also be widely used in energy, biology, medicine and other fields. (C) 2009 Elsevier B.V. All rights reserved.