In support of the U.S. Department of Energy need for new data for criticality safety applications, new high-resolution fission cross-section measurements of 233U have been made at the Oak Ridge Electron Linear Accelerator. The measurements were carried out over a 0.4-eV to 700-keV energy range at the 80-m flight station using a fission chamber. Corrections were made for experimental effects to obtain the average fission cross section in this energy range. Results are compared to previous measurements.