Photovoltaic response has been observed inp‐njunctions of PbxSn1−xTe at wavelengths up to 9.5 &mgr; at 77°K and up to 12 &mgr; at 12°K. These results together with previous photoluminescence data and the proposed model for the band structure of PbxSn1−xTe (ref. 1) indicate that these alloys have considerable potential for efficient infrared detection throughout the 8 to 14 &mgr; atmospheric window and well beyond.