This paper describes historical overview and recent activity on “plasma electrochemistry”, which involves materials processing with plasmas in contact with liquids. Nano-materials synthesis and organic-pollutant decomposition are the most active application areas. The most important part of the plasma electrochemistry is the plasma/liquid interface. The physicochemical processes near the plasma/liquid interface have been gradually clarified through experiments and numerical simulations. These are briefly described in this paper together with future issues for understanding effects of electric double layer and nano-scale steep density gradient.
