Three novel phenylacetylenes having two hydroxyl groups via different kinds of spacers between the two hydroxyl groups and benzyl group were synthesized and polymerized. Two of the resulting polymers having oxyalkylene spacers between the hydroxyl group and benzyl group had good membrane forming ability, relatively high oxygen permselectivity and high oxygen permeability. By introducing the oxyalkylene spacers, the membrane forming abilities and oxygen permselectivity were enhanced. Oxygen permselectivity (P-O2/P-N2 = 2.67) of the polymer membrane having the longest spacers was higher than that (2.19) of polymer without any spacers. It may be because the columnar content and then defects decreased when the cis-cisoid conformation was changed to cis-transoid conformation. In addition, by decreasing the columnar content of the membrane from the polymer without any spacers, which could be controlled by conditions in membrane preparation, the membrane forming ability and oxygen permselectivity were effectively enhanced (from 2.19 to 2.61) without any drop of oxygen permeability. (C) 2014 Elsevier Ltd. All rights reserved.