Asymmetric hollow fibre membranes of structurally modified polybenzimidazole (PBI) were fabricated for the first time using dry-jet wet spinning technique. The modified-PBI membranes for gas separation were shown to exhibit higher flux, but lower selectivities compared to conventional PBI membranes. However, further post modification of these hollow fibre membranes by crosslinking reaction substantially enhanced the ideal gas-pair selectivities. The crosslinking reaction was demonstrated to improve not only the gas permeation properties, but also the mechanical properties of the modified-PBI hollow fibre membranes. The modified-PBI membranes showed good combinations of gas flux and selectivities for industrially important gas pairs such as CO2/N-2, O-2/N-2 and H-2/N-2 with the ideal selectivities of 37, 8 and 115.9, respectively, while the permeation fluxes of H-2, O-2 and CO2 were at about 12.97, 0.89 and 4.1 GPU, respectively. Development of such modified-PBI hollow fibre membranes with improved gas permeation properties in combination with their known excellent thermal and chemical properties depicts their potential for gas separation applications at harsh environment. (c) 2012 Elsevier B.V. All rights reserved.