The Langmuir-Blodgell (LB) technique was utilized to control surface properties of narrow microchannel walls at the molecular scale. Fluorinated amphiphilic polymer (pC7F15MAA) was synthesized and its ultrathin films were prepared by the LB technique. Microchannel was fabricated with glass substrates. A laminar flow of water in hydrophilic and hydrophobic microchannels was monitored in situ using an. optical microscope equipped with a digital CCD camera. Shape of meniscus was clearly monitored with 250 ms time-resolution. The fluorinated polymer LB film can be a good candidate to control water motion in the microchannel.