High-temperature water electrolysis in a solid oxide electrolysis cell (SOEC) can be an efficient way of producing hydrogen, especially if it can be coupled with a renewable energy source. In this study, the performance of a nickel-doped, A-site deficient lanthanum strontium ferrite (La0.7Sr0.2FeO3) was investigated as an SOEC cathode. Electrolysis of H2O was carried out using a cathode stream containing 3% H2O/He at 800 degrees C and at various current densities. It was found that La0.7Sr0.2FeO3 has a lower Faradaic efficiency for hydrogen production than the Ni-doped cathode for which the efficiency reaches 100%. XRD shows that the undoped sample forms a nonconducting La2O3 secondary phase which affects the electrochemical performance negatively. On the nickel-doped sample, however, a B-site metal phase and a Ruddlesden-Popper phase with mixed electronic and ionic conductivity are formed, which enhances the electrochemical performance of the cathode.