The capture cross section of 238U has been measured absolutely at a neutron energy of 30 keV using kinematically collimated neutrons from the 7Li(p, n) 7Be reaction near threshold. Activation techniques were used to determine both the number of capture events and the number of neutrons that occurred during the irradiation. The result of the 238U capture cross section measurement is 479 ± 14 mb at 30 keV. In addition, the shape of the 238 U capture cross section has been measured for neutron energies from 25 to 500 keV using neutrons from the 7Li(p, n)7 Be reaction. The capture reactions in the 238 U target were detected using a large liquid scintillator tank and time-of-flight techniques. The relative neutron flux was measured using a flat response neutron detector. The cross-section shape measurement was normalized to the present absolute measurement at 30 keV. The present measurement has been compared with several measured values, theoretical calculations, and compiled values of the 238U capture cross section as given by other authors.