For selected compositions of the variable band‐gap alloy semiconductor In1−xTlxTe the photoconductive response has been observed over the special range from 0.6 to 12.2 mm. The band‐gap energy was found to decrease linearly as a function of composition from 0.72 eV atx= 0.48 to a zero band‐gap atx≃0.06. All compositions in this range were found to beptype.