In this work the A-site deficiency limit for undoped SrTiO3, calcined in air or reducing atmosphere, was investigated. XRD and SEM analyses showed that when using the solid-state synthesis route it was difficult to achieve any A-site deficiency. Even very small deviations frorn unity in the Sr/Ti-ratio resulted in impurity phases. The effects of Sr/Ti-ratio on the performance of SrTiO3 anodes for solid oxide fuel cells (SOFCs) was investigated by impedance spectroscopy with cone-shaped electrodes. The electrocatalytic activity of the SrTiO3 cone samples, With various amount of reduced titanium dioxide phases (Maoneli phases), was investigted for oxidation of H, at 700 degrees C. High temperature treatment at 1000 degrees C, between the measurements at 700 degrees C, showed that high content of Magneli phases leads to faster degradation of the activity. The suitability for using cone-shaped electrodes as a tool for investigating electrode materials is discussed. (c) 2006 Elsevier Ltd. All rights reserved.