The effect of a surface temperature gradient on the water vapour pressure over glycerol-water mixtures has been measured for glycerol concentrations in the range from 80% to 94.5% by weight. Graphs of Delta P versus Delta T are linear, for both positive and negative Delta T, at thicknesses of the vapour layer up to at least eight mean free paths. Compound formation, which for sulfuric-acid/water caused the measured heat of transport to decrease markedly at high acid concentrations, has no discernible effect on the measured heat of transport for glycerol-water mixtures. (c) 2006 Elsevier B.V. All rights reserved.