Temperature dependent measurements of the in-plane photovoltage (IPV) arising from Fermi level fluctuations constitute a powerful tool for determining surface and bulk states and trap activation energies in nominally undoped semiconductors. In this work we report the first IPV measurements on high quality InN grown using the MBE technique. The temperature dependent IPV results coupled with Hall mobility and carrier density measurements provide ample evidence for the existence of a high density of states within the range 54 to 68 meV below the conduction band. Temperature dependent PL measurements indicate a band gap of 0.77 eV where a very weak temperature dependence is observed between 77 and 300 K. These results are shown to be in accord with the lPV measurements. (C) 2004 Elsevier Ltd. All rights reserved.