The gas-phase infrared spectrum of the linear molecule 13C 5 has been studied in the region of the ν 3 vibration around 2086 cm -1. The results were obtained using a tunable diode laser spectrometer and a hollow cathode discharge in a flowing mixture of acetylene and helium. Two bands were observed and assigned: the ν 3 fundamental and the associated ν 3 + ν 7 - ν 7 hot band. The study of ν 3 in isotopically substituted C 5 provides more experimental data for this species, which may be difficult to obtain otherwise because of the predicted weakness of its other infrared transitions. The band origins and rotational constants for 13C 5 are consistent with those from a matrix-isolation study of C 5 isotopes and gas-phase studies of 12C 5. By combining the 13C 5 and 12C 5 results it is possible to determine an experimental Be = 2548.7 MHz for 12C 5. The ν 3 fundamental band origin of 13C 5 was determined to be 2085.769 cm -1.