The novel highly permeable composite membranes with a thin selective layer made of poly(1-trimethylsilyl-1-propyne) (PTMSP) on polysulfone hollow fiber support were proposed for application in gas-liquid membrane contactor for ethylene/ethane separation. The effects of AgNO3 concentration in aqueous absorbent and its velocity on the ethylene mass transfer coefficient were evaluated. High ethylene permeance (83 GPU) at ethylene recovery of 44% was achieved. Six months of membrane contactor operation revealed only 24% drop in the overall mass transfer coefficient. The contributions of membrane and liquid phase to the overall mass transfer resistance were estimated. The contributions were found to be comparable values.