AgBiI4 and Ag3BiI6 were synthesized by solvothermal reaction from AgI and BiI3 in diluted HI-solution (20 %) at a temperature of 160 degrees C. The greyish-black crystals grow as octahedra (Ag-BiI4) or hexagonal/trigonal platelets (Ag3BiI6). AgBiI4 crystallizes in space group Fd (3) over barm with a = 1222.3(1) pm (300 K) and Z = 8 whereas Ag3BiI6 shows the space group R (3) over barm with a = 435.37(6) pm, c = 2081.0(4) pm (300 K) and Z = 1. Both crystal structures show stacking sequence abcabc... of hexagonal layers containing Iodine. Bismuth and silver are sharing octahedral sites with different mass ratio in both structures. The part of silver which could be localized varies with temperature. This behaviour indicates mobility of silver within the crystal structure. The ionic conductivity of AgBiI4 is explored. AgBiI4 and Ag-3. BiI6 show close structural relationship, with AgBiI4 as a variant with a higher degree of order.