In this paper, detector-grade CdMnTe:In (CMT:In) single crystals were annealed under Te atmosphere with various annealing times. The results indicated that the density of Te inclusions had not changed as the annealing time increased, whereas the resistivity exhibited an initial increase followed by a decrease. The conduction type was changed from weak n-type conduction in as-grown crystal to p-type conduction in 60 h annealed crystal. The lR transmittance decreased obviously as the annealing time increased. In the PL spectra, the obvious reduction of the intensity of (D degrees,X) peak and the increase of the intensity of the D-complex peak in the annealed CMT:In crystals indicated a degradation of the crystal quality. The energy resolution of the detector fabricated with 15 h annealed crystal was improved, whereas the mu tau values of the detectors fabricated with all annealed crystals were reduced. Specially, the characteristic peak of Am-241 gamma-ray could not be observed in the detectors fabricated by 60 h annealed crystals. Therefore, optimal annealing temperature and the duration are 773 K and 15 h, respectively. (C) 2015 Elsevier B.V. All rights reserved