In SOFC research, it is well know that deconvoluting the contributions of the cathode and anode to the total electrode performance is of significant importance, but is also extremely challenging because of the overlap of reaction time constants from both electrodes. Due to the difficulty in placing a reference electrode, currently there are two approaches to address this challenge. The first approach is to use the distribution of relaxation times (DRT) to analyze the spectra acquired from electrochemical impedance spectroscopy (EIS). The second method is to measure the SOFC performance by changing the oxygen partial pressure while other operating parameters are fixed. In doing so, one assumes that the changes in EIS spectra are resulted from the change of cathode performance. In this presentation, a theoretical model is developed to show what the requirements are for this assumption. Various cathode- and anode- materials are then utilized to validate our theoretical analysis. DRT analysis is used to cross validate this model. Criteria on deconvoluting electrode performance will be provided.