Effect of MnO2 type on catalytic phenol removal in bioelectrochemical systems (BES) was firstly investigated. Three MnO2 types (namely alpha, beta, and gamma) were prepared via hydrothermal methods, and polypyrrole (PPy) was used as a conductive wrapping to anchor MnO2 onto the surface of graphite felt (GF) electrodes. A BES equipped with GF/PPy/beta-MnO2 resulted in superior phenol degradation and power generation. High BET surface area and electrocatalytic activity of beta-MnO2 played a key role.