Transparent conducting oxide of In2O3.(ZnO)k (indium zinc oxide; IZO) ceramics have various homologous compounds with different k values, and the phase relationship between the compounds changes with temperature [J. Am. Ceram. Soc. 81 (1998) 13 10]. In this study, IZO ceramics were reaction-sintered without calcination process. Different sintering processes of the rapid rate sintering and the conventional sintering were employed. In the case of the rapid rate sintering, solid state reaction was not completed during heating up which led to poor densification. In the case of the conventional sintering reaction was completed during heating up which was favorable in densification. From the experimental result, it was verified that reaction occurs prior to densification in the reaction sintering of IZO. (C) 2004 Elsevier B.V. All rights reserved.