Li2TeS3 and Li2TeSe3 were synthesized by the reaction of stoichiometric amounts of Li, Te and Q (Q = S, Se) in the ratio 2 : 1 : 3. Both products are extremely air and moisture sensitive. The crystal structures were determined by single crystal X-ray diffraction at room temperature. Red Li2TeS3 and metallic black Li2TeSe3 crystallize isotypically in the monoclinic space group P2(1)/c (no. 14) with four formula units per unit cell and the lattice parameters: Li2TeS3: a = 5.437(1) angstrom, b = 11.564(1) angstrom, c = 7.907(1) angstrom, beta = 91.57(1)degrees, V = 496.96(1) angstrom(3); Li2TeSe3: a = 5.658(1) angstrom, b = 12.032(1) angstrom, c = 8.278(1) angstrom, beta = 92.690(1)degrees, V = 562.93(1) angstrom(3) (data at 20 degrees C). The atomic arrangements persist of isolated trigonal pyramidal [TeQ(3)](2-) anions which are arranged in layers. Li is coordinated by six Q atoms from four (Li1) or five (Li2) different thiotellurate or selenidotellurate units, respectively. Impedance spectroscopic measurements in the temperature range 90 - 200 degrees C show that Li2TeS3 is a semiconductor with an activation energy of 0.71 eV Li2TeSe3 is a mixed conductor with an activation energy of 0.68 eV.