Accurate and reliable tritium management is of basic importance for the correct operation conditions of the blanket tritium cycle. The determination of the hydrogen isotopes concentration in liquid metal is of high interest for the liquid breeder blankets (like Helium-Cooled Lithium–Lead or Dual Coolant ‘He/Pb17Li’ blankets) correct design and operation. Sensors based on solid state electrolytes can be used to that purpose. These types of sensors offer quick and easy to measure signals, high chemical stability and temperate depending ionic conductivity. Potentiometric hydrogen sensors based on solid state electrolytes were previously studied at the Electrochemical Methods Laboratory at Institut Químic de Sarrià (IQS) at Barcelona. Due to the satisfactory obtained results, amperometric configuration was also evaluated. The probes are based on solid state electrolytes and are considered Proton Exchange Membranes—PEM. These electrolytes are perovskite type materials with electrical carriers being: positive holes, excess electrons, oxide ion vacancies and interstitial protons which interact with oxide ions. In the present work, solid state electrolytes for potentiometric sensors have been synthesized in order to be tested as PEM in amperometric H-probes. Amperometric measurements have been performed at different hydrogen partial pressures (5 to 55 mbar), different temperatures (500 °C to 650 °C) and applying different polarization potentials to the sensor.