The fabrication of tubular poly-2-vinylimidazoline (PVI) composite reverse osmosis (RO) membranes is described. Self-directing optimization experiments were used to derive a formulation for these membranes. Two types of membranes were prepared from two different PVI precursors, each interfacially crosslinked with 3-(chlorosulfonyl)benzoyl chloride. Very good RO properties were exhibited by the "optimized" membranes : in one case 99.4% NaCl retention and a permeate flux of 500 L/m2/d were obtained. Conditions of evaluation were : 2 MPa, 20-degrees-C, 2 g/L NaCl feed, 1 m/s linear flow rate.