From the reaction of the metallic elements in molten alkali metal/polychalcogenide fluxes, we have synthesized KCuCe2S6 (I) and K2Cu2CeS4 (II). Isolated from a 2/0.5/1/8 mixture of K2S/Cu/Ce/S heated at 270 degrees C for 6 d, I crystallizes in the space group C2/c (no. 15) with a = 6.859(2) Angstrom, b = 21.154(2) Angstrom, c = 6.8599(8) Angstrom, beta = 105.41(2)degrees, and Z = 4. The structure of I features (CuCe2S6)(n)(n-) anionic layers composed of [CeS8] bicapped trigonal prisms connected in the ZrSe3 fashion with Cu+ residing in tetrahedral sites within the layers and K+ cations in the interlayer gallery. Diffuse reflectance measurements have shown an approximated band gap of 1.8 eV for I, and magnetic studies exhibit Curie-Weiss paramagnetic behavior at temperatures above 160 K with mu(eff) = 3.08 mu(B)/formula. Isolated from a 4.2/0.5/0.25/8 mixture of the above reagents heated at 260 degrees C for 5d, II crystallizes in the C2/m space group (no. 12) with a = 14.320(3) Angstrom, b = 3.961(1) Angstrom, c = 7.496(2) Angstrom, beta = 109.77(2)0, and Z = 2. Compound II is also a layered structure in which Ce atoms, octahedrally coordinated by S, and Cu, tetrahedrally coordinated by S, form anionic layers related to Mg2SiO4 (olivine) with K+ in the interlayer gallery. From magnetic susceptibility studies, a mu(eff) of 2.38 mu(B) was estimated above 150 K corresponding to the value for a lone Ce3+. The compound’s oxidation states are formalized as K-2(Cu1+)(2)(Ce3+)(S2-)(3)(S1-) Below 150 K, the material shows non-Curie-Weiss behavior, exhibiting a decreasing mu(eff). Thermopower studies on II show p-type carriers; however, the conductivity is low and increases with increasing temperature, suggesting a low carrier mobility possibly arising from small polaron formation.