Abstract. The neutron capture cross sections and the capture gamma-ray spectra of 127 I and 133 Cs at incident neutron energies from 15 to 100 keV have been measured by the time-of-flight method. Capture gammarays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive capture yields. The capture cross sections of 127 I and 133 Cs were determined using the standard capture cross section of 197 Au. The total errors of the cross sections were 3.8-5.1%. The obtained cross sections were compared with evaluated values in JENDL-4.0 and ENDF/B-VII.1. For 127 I, the energy dependence is different between the present results and the evaluations. For 133 Cs, the evaluated values in JENDL-4.0 agree with the present results but the evaluated values in ENDF/B-VII.1 are smaller than the present results by 14%-18%. The capture gamma-ray spectra of 133 Cs and 127 I were derived by unfolding the pulse height spectra with detector response functions.