Two new potassium uranyl molybdates K 2 (UO 2 ) 2 (MoO 4 )O 2 and K 8 (UO 2 ) 8 (MoO 5 ) 3 O 6 have been obtained by solid state chemistry . The crystal structures were determined by single crystal X-ray diffraction data, collected with MoKα radiation and a charge coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least square method on the basis of F 2 for all unique reflections, with R 1 =0.046 for 136 parameters and 1412 reflections with I>=2σ(I) for K 2 (UO 2 ) 2 (MoO 4 )O 2 and R 1 =0.055 for 257 parameters and 2585 reflections with I>=2σ(I) for K 8 (UO 2 ) 8 (MoO 5 ) 3 O 6 . The first compound crystallizes in the monoclinic symmetry, space group P2 1 /c with a=8.250(1)A, b=15.337(2)A, c=8.351(1)A, β=104.75(1) o , ρ m e s =5.22(2)g/cm 3 , ρ c a l =5.27(2)g/cm 3 and Z=4. The second material adopts a tetragonal unit cell with a=b=23.488(3)A, c=6.7857(11)A, ρ m e s =5.44(3)g/cm 3 , ρ c a l =5.49(2)g/cm 3 , Z=4 and space group P4/n.In both structures, the uranium atoms adopt a UO 7 pentagonal bipyramid environment, molybdenum atoms are in a MoO 4 tetrahedral environment for K 2 (UO 2 ) 2 (MoO 4 )O 2 and MoO 5 square pyramid coordination in K 8 (UO 2 ) 8 (MoO 5 ) 3 O 6 . These compounds are characterized by layered structures. The association of uranyl ions (UO 7 ) and molybdate oxoanions MoO 4 or MoO 5 , give infinite layers [(UO 2 ) 2 (MoO 4 )O 2 ] 2 - and [(UO 2 ) 8 (MoO 5 ) 3 O 6 ] 8 - in K 2 (UO 2 ) 2 (MoO 4 )O 2 and K 8 (UO 2 ) 8 (MoO 5 ) 3 O 6 , respectively. Conductivity properties of alkali metal within the interlayer spaces have been measured and show an Arrhenius type evolution.