The development of outstanding H-2 -sensing materials is vital for the realization of eco-friendly devices using H-2-based energy. ZnO nanofibers have excellent H-2-sensing performance. In this study, we synthesized a series of Co3O4-loaded ZnO nanofibers with the formula (1-x)ZnO-xCo(3)O(4)(x = 0.03, 0.05, 0.1, and 0.15, representing the molar ratio of Co3O4) via electrospinning to improve the H-2-sensing properties of pristine nanofibers. The sensing results indicated that a sensor with a nominal composition of 0.95ZnO-0.05Co(3)O(4) had the highest response of similar to 133 to 10 ppm H-2 gas, with good H-2 selectivity. The main mechanisms underlying the excellent H-2-sensing capability of the optimized gas sensor involved ZnO surface/grain boundaries and Co3O4. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.