IrO2-loaded porous foam-like Ga1.4In0.6O3 nanofibers with ultrathin pore walls were synthesized via a simple electrospinning and impregnation method for the detection of formaldehyde. This gas sensor based on IrO2-loaded Ga1.4In0.6O3 nanofibers showed excellent sensitivity and selectivity towards trace formaldehyde. Especially, the response of the gas sensor based on 1% IrO2-Ga1.4In0.6O3 nanofibers is as high as 46 towards 10 ppm formaldehyde, while it is only 7 for the gas sensor based on Ga1.4In0.6O3. Moreover, the gas sensor based on 1% IrO2-Ga1.4In0.6O3 exhibited remarkable selectivity towards formaldehyde. The high sensitivity and good selectivity of IrO2-loaded porous Ga1.4In0.6O3 nanofibers could be attributed to the specific catalytic activity of IrO2, the unique composition and the ultrathin structure of Ga1.4In0.6O3. (C) 2017 Elsevier B.V. All rights reserved.