The aim of the study was to investigate the effect of crude extracts of Thymus vulgaris on wood surface physicochemical characteristics. Thus, the Lifshitz-van der Waals (gamma(LW)), acid-base (surface tension components Delta Giwi, electron donor (gamma(-)) and electron acceptor (gamma(+)) parameters of untreated and treated wood were assessed using contact angle measurement. The main results showed that all T. vulgaris extracts are able to change wood surface properties. Indeed, the samples treated with the product obtained by maceration and ultrasound indicated the hydrophilic character (theta(w) = 29.7 +/- 0.3, Delta Giwi = 17. 78 +/- 0.48 mJ/m(2) and theta(w) = 18.2 +/- 0.2 degrees, Delta Giwi = 30.62 +/- 0.31 mJ/m(2)) respectively, and had less contact angle values than that of untreated wood (theta(w) = 86.0 +/- 0.2 degrees). In addition, this treatment has made the wood more donor (gamma(-) = 44.76 +/- 0.3 mJ/m(2) and gamma(-) = 53.80 +/- 0.3 mJ/m(2)) than the electron acceptor compared to sample control (gamma(+) = 2.03 +/- 0.04 mJ/m(2)). Finally, the effect of the extract obtained by ultrasound was found to be more important and significant than those recovered by classical extraction.