Three-dimensional macroporous TiO2 was synthesized by a sol-gel procedure using polystyrene colloidal crystals as templates. SEM showed that a face-centered Cubic (FCC) 3D macroporous structure was obtained. Horseradish peroxidase (HRP) was successfully immobilized on the surface of an optically transparent electrode (OTE). Photoelectrochemical properties were characterized using a three electrodes system and an ultraviolet lamp. The HRP/TiO2/OTE displays a rapid photocurrent response, approximately 178.7 nA, under UV illumination (380 nm). The sensitivity of H2O2 detection was 70.04 mu A/mM without UV illumination, and it increased to 102.97 mu A/mM when illuminated by UV. The amperometric response was also enhanced. The high response was due to the good biocompatibility of TiO2 and excellent photoelectrical property and the large effective surface of the three-dimensionally ordered macroporous structure. (C) 2008 Elsevier Ltd. All rights reserved.