The electrical properties of pure, hydrogenated and hydrophobically modified polyethylene glycole (PEG) thin films under changing relative humidity conditions are investigated by de measurements. Perfluoroalkylethylalcohol is used as the hydrophobic additive. The conductivity of all samples increases gradually up to around 70% relative humidity, beyond which there exists a steep increase. For the pure PEG samples, after 75%, the conductivity shows irregularities with respect to the increase in the relative humidity. The irregularities subside in the hydrogenated as well as the hydrophobically modified PEG samples, while in the latter the steep increase in conductivity shifts to higher values of relative humidity with the increase of perfluoroalkylethyl alcohol concentration in the film. (c) 2006 Elsevier B.V. All rights reserved.