Controlling the wetting properties at the three-phase interface is important for improving the performance of alkaline fuel cells. The meniscus of a potassium hydroxide droplet was formed on a nickel electrode, and the interference fringe during the oxygen reduction reaction was observed by confocal laser microscopy. The high spatial resolution of the microscope revealed thin film formation at the meniscus front interface. The thickness decreased with increasing cathodic potential. The generation of microscopic convection by interfacial surface tension may affect mass transfer in the thin film.