Thin tin oxide film with nano-size particle was prepared on silicon substrate by hydrothermal synthetic method and successive sol-gel spin coating method. The fabrication method of tin oxide film with ultrafine nano-size crystalline structure was tried to be applied to fabrication of micro-gas sensor array on silicon substrate. The tin oxide film on silicon substrate was well patterned by chemical etching upto 5 mum width and showed very uniform flatness. The tin oxide film preparation method and patterning method were successfully applied to newly proposed two-dimensional micro-sensor fabrication. (C) 2003 Elsevier B.V. All rights reserved.