The aim of this work was to investigate the effects of heat treatment applying hot air at different temperatures and durations on the morphology and the performance of polyetherimide (PEI) hollow fiber membrane contactors for CO2 separation. The membranes were fabricated via a wet spinning into non solvent bath technique. Then, the membranes were heat treated by exposing them at 80,120 and 160 degrees C for all time intervals of 5, 15 and 30 min under a hot air atmosphere. To study the influence of the hot air on the membranes structural parameters and the performance of the membranes they were characterized by: gas permeation test, membrane overall porosity measurement, critical entry pressure of water (CEPw) and gas absorption via a membrane contacting process. The experimental results revealed that, the greatest effect on the membranes structure was observed in the shortest time duration and the lowest temperature i.e. 5 min and 80 degrees C, which exhibited a pore size of 49 (nm), a maximum effective surface porosity of 26.8 (1/m) and a CEPw of 3.4bar. Also, for all the time periods and the temperatures tested, the density of the fibers reduced and the CEPws along with the overall porosities increased. In conclusion, applying heat treatment technique on PEI hollow fiber membranes is a simple and easy approach to improve the performance of hollow fiber membrane contactors for CO2 removal. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.