Abstract: In this paper are given the method of preparation of U-ion selective electrode and its main properties related to the porpsity and size of the carrier, length of carrier, concentration of ion exchanger in active solution and the benzoate concentration used. The electrode slope is 56.4±2mV for 5 ×10-4M UO2 2+, and 52±1mV for 1×10-4M UO2 2+, and the electrode potential is liner with U concentration in the range 2×10-6-1×10-4M. This kind of electrode has high sensitivity, ready response, good selectivity and little temperature effect. It can be used in the determination of micro-amount of U in mineral water and process solutions.