Removal of olefin gaseous compounds such as ethylene, propylene, 1-butene and butadiene from paraffins is one of the most crucial issues in the petrochemical industries. The supported liquid membrane of silver nitrate solution supported in PVDF microfilter membrane was used for 1-butene/isobutane separation in the current study. The effects of silver nitrate concentration, trans-membrane pressure and gaseous feed stream's humidity were investigated on the membrane separation performance. According to the results, as the salt concentration increased from 0 to 3M, 1-butene permeance and 1-butene/isobutane selectivity were increased from 1.96 x 10(-5) to 0.0607 gpu and 0.0004 to 1380, respectively. In the liquid membrane containing aqueous solution of 1M silver nitrate, 1-butene/isobutane selectivity were found as 100 and 330 for the dry and humidified feed gas streams. Cu(NO3)(2).3H(2)O salt was used simultaneously with the silver salt in the aqueous liquid membrane in order to increase the long-term stability of the membrane in addition to the feed stream humidification. As the both salts were used simultaneously in 1 M concentration, 1-butene/isobutane selectivity decreased slightly from 439 to 399, while the 1-butene permeance increased from 0.0227 to 0.075 gpu, during 4 h continuous operation. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.