PURPOSE: To prepare the titled novel compound, by mixing crystalline or amorphous TiO2 with a Na compound which is decomposed into Na oxide and a gaseous compound with heat at a specific atomic ratio, heating the mixture to effect the degassing, and then heating at a specific temperature range in a reducing gas stream.

CONSTITUTION: Crystalline or amorphous TiO2 is mixed with a compound which is decomposed into Na oxide and a gaseous compound with heat, e.g. Na2CO3, Na2C2O4, etc. at a Na:Ti atomic ratio of 0.16W0.25. The mixture is degassed by heating at or above the decomposition temperature of the Na compound, and then heated at 900W1,200°C in a reducing gas stream containing H2 to obtain the defect-type hydrogen-sodium-titanium bronze compound of formula wherein X is 0.15W0.7, Y is 1.3W2 and Z is 0.3YW0.55Y. The compound contains a large amount of oxygen defects.