Abstract Values of the optical energy gap E 0 of AgInTe 2 as a function of temperature T in the range 10 to 300 K are obtained by optical absorption measurements. The variation of E 0 with T is fitted well by a Manoogian‐Leclerc equation of the form E 0 (0) − E 0 ( T ) = UT + V φ (coth φ/2 T − 1). Values of (d E 0 /d T ) 1 , the electron–phonon interaction contribution to the variation of the energy gap with temperature, and (d E 0 /d T ) 2 , the lattice dilation contribution, are obtained from the V φ and U terms, respectively. From these values of (d E 0 /d T ) 1 and (d E 0 /d T ) 2 , values are determined for the acoustic deformation potentials of the conduction band C e and the valence band C h .