To further develop sensing materials for the detection of reducing gases like NH3 and H2S and improve their response efficiency and selectivity, mesoporous In2O3@CuO composite multijunctions nanofibers (ICCNs) was synthesized by an electrospinning approach with a subsequent thermal treatment. Comparison was made with the one-dimensional (1D) pristine CuO multijunctions nanofibers (NFs). It was found that the CuO NFs have many p-p homojunctions and lots of chemisorbed oxygen, allowing for excellent gas sensing behaviors towards H2S at room temperature (RT). Interestingly, the ICCNs' sensors favor to detect NH3 gas. Amongst them, ICCN-5 (short for the sensor composite where the molar ratio of Cu: In is 100: 5) behaves very fast response, excellent selectivity and good stability (within 30 days) toward 10 ppm NH3 at RT. The significantly enhanced sensing property of ICCNs to NH3 could be attributed to the synergistic effect of In2O3 promoter, multijunctions and unique mesoporous structure of NFs. Our studies demonstrated that 1D-CuO and ICCN-5 sensors were promising candidates of practical detectors to H2S and NH3 at RT. (C) 2017 Elsevier B.V. All rights reserved.