A total absorption NaI(Tl) gamma‐ray spectrometer has been assembled and has been tested over the range 0–10 Mev with thermal neutron capture gamma rays. It employs an 8‐in. diam by 12‐in. NaI(Tl) anticoincidence mantel. The measured width at 8.5 Mev is 3% (full width at half‐maximum). Typical spectra are presented. Measurements of efficiency, line shape, and resolution are analyzed. The usefulness of this spectrometer for analysis of complex spectra at high efficiency is demonstrated.