We report on the optical and charge transport properties of novel alkali metal chalcogenides, Cs 2Hg 6S 7 and Cs 2Cd 3Te 4, pertaining to their use in radiation detection. Optical absorption, photoconductivity, and gamma ray response measurements for undoped crystals were measured. The band gap energies of the Cs 2Hg 6S 7 and Cs 2Cd 3Te 4 compounds are 1.63 eV and 2.45 eV, respectively. The mobility-lifetime products for charge carriers are of the order of ∼10 -3 cm 2/V for electrons and ∼10 -4 cm 2/V for holes. Detectors fabricated from the ternary compound Cs 2Hg 6S 7 shows well-resolved spectroscopic features at room temperature in response to γ-rays at 122 keV from a 57Co source, indicating its potential as a radiation detector.