For oxygen reduction reaction (ORR), constructing porous catalysts are highly important for mass transfer inside. However, the various porous structures usually possess significantly different water buffer efficiency, that is, the antiflooding capability, for which one is still difficult to give a quantitative evaluation. In this work, we designed a special rattle-drum like working electrode, by which an exactly quantitative assessment on the mass transfer efficiencies can be conducted. Particularly, ordered macro-mesoporous Pt/C shows quantified mass transfer and antiflooding efficiency to be four times high as that of the commercial one. This observation should be attributed to their different pore characteristics, as the dual-porosity Pt/C has 3.4 times the pore volume of the commercial one, together with regular pore arrangement. Simultaneously, it also demonstrated excellent durability, indicating that the macro-mesoporous Pt/C indeed owns high stability in both antiflooding and durability. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 2881-2889, 2018