Binary mixtures with a non-linear dependence of the surface tension with temperature were investigated as potential working fluids for wicked heat pipes to take advantage of Marangoni effect. Model experiments were carried out using quartz cuvette and glass tubes filled with different solutions and subject to thermal gradient: a mass flow directed towards hot zones along vapor-liquid interface was observed, while surface temperature profiles were recorded with an IR camera. Experiments on thermal performance of commercial heat pipes finally showed that using suitable binary Mixtures better performances can be achieved in comparison with heat pipes filled with water. (C) 2008 Elsevier Ltd. All rights reserved.