Highly hydrophobic surfaces with nanoscale roughness were prepared by coating two fluoroalkylsilanes (FAS17 and FAS3) respectively onto boehmite deposition layers. The droplet shape change on the surface was then observed with application of voltage between the droplet and the coating surfaces. The wetting mode transition on FAS3 coating advanced continuously once the applied voltage exceeded 120 V, whereas that on FAS17 coating at less than 200 V. The droplet shape changed with sustaining air phase at the solid-liquid interface.