This report covers Phase V of a continuing program to apply a new liquid membrane process called coupled transport to the recovery of metals from hydrometallurgical leach solutions. During this phase, a membrane system of moderate scale was constructed and fieldtested at the Exxon Highlands Mine and Mill Company site near Douglas, Wyoming. The test unit contained four hollow-fiber membrane modules, each with 100 ft2 of membrane area. In the field tests, about 1,000 gallons per day of leach solution was processed. The unit was operated on the leach solution for about 50 days. Leach solution entering the unit contained 100 ppm uranium. This concentration was reduced to about 5 ppm by coupled-transport treatment, and the uranium was concentrated to about 2 wt % as a uranyl carbonate product. Under these conditions, a transmembrane uranium flux of about 2.5 Lb/ft2 per year was obtained. An economic analysis showed that the cost of recovering uranium from this leach solution via coupled transport is about $1.20 Per pound. At higher concentrations the cost is reduced; for example, at 1,000 ppm the cost of uranium recovery is about $0.30 Per pound.