The cover picture image by José M. Serra and Vicente B. Vert of the Universidad Politecnica de Valencia (Spain) is based on their research towards highly active oxygen activation fuel-cell electrocatalysts. In their Communication on p. 957, they describe how the screening of a well-designed combinatorial library of crystalline catalysts reveals unexpected cooperative effects between different promoters. The experimental design chosen is a quaternary mixture diagram (solid tetrahedron) and the outcome of the screening is the identification of optimized ternary crystalline compounds combining high electrochemical activity and relatively low activation energy. These features suggest that the materials are well-suited for operation as fuel cell cathodes at intermediate temperatures (550–650 °C)—as shown in the work—and as catalytic layers on oxygen-permeable membranes. The work is supported by physico-chemical and structural characterization as well as data modeling, including neural networks.