Abstract: Nanocrystalline powder of In2O3 mixed with αFe2O3 is prepared by chemical coprecipitation, effects of αFe2O3 on the conductance and gassensing properties of In2O3 are investigated. The results demonstrate that partial solid solution In2－xFexO3（0≤x≤0.40）can be formed between αFe2O3 and In2O3; Partial lattice substituting of Fe3＋ to In3＋ can notably enhance the combining force between anion and cation, it causes oxygen vacancy to decrease, free electron density to be reduced and the conductance to be poorer(to see Fig.2). The sensitivity of sensor, which is prepared with 5:5 n(Fe3＋) andn(In3＋) calcined at 800 ℃ for 4 h, to 45 μmol•L－1 C2H5OH can reach the value of 54.0. This is eight times more than that of petrol with the same concentration .

Key words: Coprecipitation, In_2－xFe_xO₃, 　Conductance, C₂H₅OH, Gas-sensing property