Photocatalytic microreactor using an anodized TiO2 nanotube/Ti bi-layered plate was fabricated. The inner diameter and length of TiO2 nanotube were controllable by the anodization voltage and time. The photocatalytic reduction of p-nitrophenol was conducted in the microreactor. The experimental results were well fitted by a model assuming parabolic velocity profile and zero-order kinetics of surface reaction. The photocatalytic activity of TiO2 nanotube was enhanced as the surface area was increased by anodization voltage and time. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.