The formation of nanobubbles on hydrophobic self-assembled monolayers has been examined in a binary ethanol/water titration using small angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The A FM data demonstrates a localized force effect attributed to nanobubbles on an immersed hydrophobic surface. This evidence is arguably compromised by the possibility that the AFM tip actually nucleates nanobubbles. As a complementary noninvasive technique, SAXS has been used to investigate the interfacial region of the immersed hydrophobic surface. SAXS measurements reveal an electron density depletion layer at the hydrophobic interface, with changing air solubility in the immersing liquid, due to the formation of nanobubbles.