Features of the nanofabrication and device formation processes utilizing the reactions at solid/liquid interfaces, such as electrodeposition and electroless deposition, were overviewed and some of the recent applications were introduced. The features of the processes were compared with those using the physical deposition processes, and then the fabrication process using “through-mask” and “maskless” approaches were explained. As for the “through-mask” processes, the microscale electrodeposition process for the fabrication of the array of mushroom-shaped metallic absorber for the high sensitive X-ray imaging sensor, the so called X-ray microcalorimeter array, was explained. The electroless deposition process of CoNiP to form the array of magnetic nano dots was also introduced. On the other hand, the maskless and electroless fabrication process of the pattern of metallic nano dots on Si wafer surfaces was also explained, which utilized the local deposition activity induced at the nanoscopic defect sites on the wafer surface.