Hierarchically porous molybdenum trioxide (MoO3) electrocatalyst is controllably synthesized by the facile hydrothermal method with the assistance of soft template (polyethylene oxide-polypropylene oxide-poly-ethylene oxide, P123). The as-prepared porous MoO3 material works as a highly efficient and bifunctional electrocatalyst for oxygen and hydrogen evolution. In oxygen evolution reaction (OER), the porous MoO3 electrode shows an overpotential reduction of 52 mV compared with precious RuO2, which is also superior to that of commercial MoO3. Besides, the electrochemical active surface area (ECSA) of porous MoO3 (2.8 cm(2)) which is three times higher than that of commercial MoO3 (0.8 cm(2)). For hydrogen evolution reaction (HER), porous MoO3 electrode exhibits a reduction of 113 mV overpotential at -10 mA cm(-2) compared with commercial MoO3. Furthermore, the ECSA value of porous MoO3 (1.4 cm(2)) is four times higher than that of commercial MoO3 (0.3 cm(2)). The bifunctional MoO3 material displays Tafel slopes of 0.44 and 0.75 times for OER and HER than those of commercial MoO3. Besides, bifunctional MoO3 material exhibits high durability for both reactions in 24 h.