Transport of uranyl ion across a bulk liquid membrane using chloroform solutions of calixarenes (as carriers) has been studied. Various factors that affect the transport have been optimised in order to obtain maximum transport. It has been observed that the use of tri-n-octyl phosphine oxide (TOPO) as a synergistic reagent showed a marked enhancement of transport of uranyl ion. Crown ether 18 Crown 6 (18C6) also exhibited synergistic behaviour when used in combination with calixarenes. The use of these synergistic reagents resulted in high transport of uranyl ion with 0.1 M nitric acid as the receiving solution. The interference from different transition metal ions was found to be negligible. The serious interference from Th(IV) could be minimised by using EDTA as masking agent. A possible application of this carrier system and transport process to the pre concentration and recovery of uranium from seawater has also been examined.