The gecko’s adhesion mechanism has been studied intensely over the past ten years. Recently it has been shown that humidity can increase the adhesion force of the gecko adhesive system. It has been pointed out that a change in hydrophobicity due to conformational changes of the toe material is responsible for this behavior. The aim of this project was to investigate the influence of hydrophobicity on the adhesion of a man-made gecko mimicking adhesive. The hydrophobicity of Polydimethylsiloxane (PDMS) has been modified by a water-argon plasma and the change of surface hydrophobicity was investigated by measuring the contact angle of the PDMS surface. Our results show that the contact angle decreases after the plasma treatment from more than 100° to about 15°, indicating a decrease in hydrophobicity. The PDMS surface recovers hydrophobicity completely within 48 hours. X-ray photoelectron spectroscopy (XPS) measurements show that incorporation of oxygen and a change in silicon binding state on the PDMS surface are responsible for the decreasing hydrophobicity. Further influence of this modification on the adhesion of gecko mimicking PDMS will be investigated by using a surface force apparatus.