Approx. 10 mL of O-18 H2O was loaded in an apparatus containing a 5 mL storage vessel, pump, Ag target attached to a cyclotron, filter, backpressure regulator, conductivity meter, several valves and ion exchange cartridges.The H2O was continuously pumped through the target during p bombardment at a rate 5 mL/min.Continuous irradiation with beam current ranging from 10 to 50 μA was conducted while pressure, temperature and conductivity were continuously monitored.Recirculating of the target H2O can increase production of F-18 in relation to consumed O-18 H2O material.Productivity can also be increased by elimination of idle periods for re-filling the target.A backpressure regulator can precisely control target pressure.This method also allows for continuous monitoring of the target material temperature, pressure, conductivity and accumulated radioactivity.Results of these observations provide important information about target performance and phys. processes taking place inside the target.