The transport of photogenerated electrons through nanocrystalline particulate TiO2 electrodes has been investigated by intensity modulated photocurrent spectroscopy, using UV light for electron-hole pair generation. The optoelectrical admittance has been compared with that obtained with nanoporous crystalline GaP electrodes in which the transport of electrons through the porous network is simply diffusive. It is found that transport of photogenerated electrons through particulate TiO2 electrodes is limited by trapping/detrapping in band gap states distributed in energy. It is argued that the electron traps are located at the TiO2/electrolyte interface.