Zeolite-templated carbon (ZTC) was used as a new nanoporous filler to prepare mixed-matrix membranes (MMMs) with polysulfone as a continuous phase. The ZTC was prepared using a synthesized zeolite-Y template and sucrose carbon source via the impregnation method. The MMMs were fabricated through a dry-jet wet spinning technique, and the ZTC loadings were varied between 0.4-0.7 wt%. The results showed that the integration of the ZTC did not change the microscopic structure of membranes. Additionally, the addition of filler did not affect the amorphous character of the polymer, while the polymer chain spacing slightly decreased. The thermal stability of MMMs improved with an increase in the glass transition temperature. The MMM at 0.4 wt% loading exhibited the best separation performances as shown from the Robeson curve, with CH4, CO2, N-2, O-2, and H-2 permeances of 5.9, 58.5, 5.0, 14.0, and 169.2 GPU, respectively. In addition, the improvements in CO2/CH4, O-2/N-2, H-2/CH4, and CO2/N-2 ideal selectivities were 290%, 117%, 272%, and 219%, respectively. On the other hand, the enhancement of the permeances and reduction in selectivities observed at 0.7 wt% loading indicated that the existence of voids was a main factor in the permeation behavior of the MMMs. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.