The photocatalytic (PC) and photoelectrocatalytic (PEC) degradations of liquid-phase rhodamine B (RhB) were investigated over titanium dioxide (TiO2) coated patterned indium tin oxide (ITO) substrate, denoted as planar ITO/TiO2/ITO device. It is found that over planar ITO/TiO2/ITO device, the PEC degradation of RhB by a bias of 1.5V is significantly increased than the PC degradation of RhB, mainly because the horizontal electric field can not only suppress the hole-electron recombination, but also act as an electric agitator to enhance the competitive adsorption of RhB onto the TiO2 surface. The results show that the planar ITO/TiO2/ITO device is an alternative way to achieve efficient degradation of dyes with simple configuration. (c) 2010 Elsevier B.V. All rights reserved.