TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The complex oxide, which does not contain water has two-dimensional layer structure containing sodium and two-dimensional triangular latticed layer of CdI2 type laminated alternately. The complex oxide having z between 0 and 0.5 (excluding 0) has ruthenium oxide two-dimensional layer structure of CdI2 type and two-dimensional triangular latticed layer containing sodium laminated alternately. The metal component ratio in the source material used as the supply source of sodium and ruthenium is same as that of metal component ratio in the complex oxide. Preferred Properties: The molar susceptibility of the complex oxide is calculated using the formula: (1-x)C1/(T-theta)+xC2, where C1 is Curie constant, T is absolute temperature, theta is number of Weiss, C2 is constant and x is 0-1, preferably 0.95 or more. Preferred Process: The source material is sealed in a tube and heated at 650-1100degreesC in inert atmosphere. The complex oxide obtained is further reacted with water.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The complex oxide, which does not contain water has two-dimensional layer structure containing sodium and two-dimensional triangular latticed layer of CdI2 type laminated alternately. The complex oxide having z between 0 and 0.5 (excluding 0) has ruthenium oxide two-dimensional layer structure of CdI2 type and two-dimensional triangular latticed layer containing sodium laminated alternately. The metal component ratio in the source material used as the supply source of sodium and ruthenium is same as that of metal component ratio in the complex oxide. Preferred Properties: The molar susceptibility of the complex oxide is calculated using the formula: (1-x)C1/(T-theta)+xC2, where C1 is Curie constant, T is absolute temperature, theta is number of Weiss, C2 is constant and x is 0-1, preferably 0.95 or more. Preferred Process: The source material is sealed in a tube and heated at 650-1100degreesC in inert atmosphere. The complex oxide obtained is further reacted with water. EXAMPLE - Sodium-ruthenium oxide (Na2RuO4) and ruthenium metal were mixed uniformly in the atomic ratio of 1:1 and charged in a platinum tube. The tube was filled with argon gas and closed. The tube was heated at 1050degreesC in an electric furnace for 90 hours and the source material was reacted. The tube was cooled to room temperature to obtain fine crystal particles of complex oxide of formula: Na1Ru1O2. The complex oxide was reacted with distilled water at room temperature for 8 hours to obtain complex oxide of formula: Na0.3Ru1O2.0.43H2O. The complex oxide had favorable electrical conductivity.