A composite polyamide reverse osmosis membrane and method of producing same. In one embodiment, the membrane is made by coating a porous polysulfone support for about 40 seconds with an aqueous solution containing 2 wt % of meta-phenylenediamine (MPD), 1 wt % 1,4-diazabicyclo[2,2,2]octane (DABCO) and 0.85 wt % methanesulfonic acid (MSA). Next, the excess MPD solution is removed, and the coated support is dipped for about 1 minute in 0.1 wt % organic solvent solution of trimesoyl chloride (TMC) in a mixture of alkanes having from 8 to 12 carbon atoms. After draining the TMC solution off, the resulting composite membrane is heated at 90.degree. C. for about 3.5 minutes and then rinsed in a basic aqueous solution at 40-60.degree. C. for 30 minutes. The resultant membrane exhibits a flux of 32.3 gfd and a salt rejection of 97.0% when used at 225 psi for an aqueous solution containing 2000 ppm of NaCl.