Metal oxides are investigated as an alternative to metal contacts on thallium bromide (TlBr) radiation detectors. X-ray photoelectron spectroscopy studies of SnO 2 /TlBr and ITO/TlBr devices indicate that a type-II staggered heterojunction forms between TlBr and metal oxides upon contacting. By using the Kraut method of valence band offset (VBO) determination, the VBOs of SnO 2 /TlBr and ITO/TlBr heterojunctions are determined to be 1:05 + 0:17 and 0:70 + 0:17 eV, respectively. The corresponding conduction band offsets are then found to be 0:13 + 0:17 and 0:45 + 0:17 eV, respectively. The I-V response of symmetric In/SnO 2 /TlBr and In/ITO/TlBr planar devices is almost Ohmic with a leakage current of less than 2.5 nA at 100 V.