As a mixed ion electronic conducting oxide, PrBaCo2O5+delta is regarded as a promising solid oxide fuel cell cathode. To further improve PrBaCo2O5+delta cathode's oxygen reduction reaction activity, porosity graded PrBaCo2O5+delta-based cathode is prepared by screen printing technology. With a porous top and a comparative denser base, oxygen ions concentration and oxygen gas concentration in the cathode can be graded distributed. This concentration gradient works as driven force which can enhance the cathode catalytic activity. And distribution of relaxation time analysis is carried out to investigate cathodes performance optimization mechanism, the result shows that gradient porous PrBaCo2O5+delta cathode's area specific resistance value is much lower than the traditional homogeneous porosity PrBaCo2O5+delta cathode. The scaffold porosity modification promotes the cathode oxygen ions transfer processes without obvious impact on the cathode oxygen surface processes. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.