CaI2(H2O)2 reacts with O-donor ligands L to yield coordination compounds of the type {[Ca(H2O)2L4]I2}n/, (1: L = CH3COOC2H5, n = 1; 2: L = THF, n = 2). Both compounds feature a coordination number of six around the calcium atom with two water molecules in axial positions and four ligands L in equatorial positions of a tetragonal bipyramid. Due to only a slight variation in the arrangement of the cationic units [Ca(H2O)2L4]2+, hydrogen bonds can be built up between them and the iodide anions in different ways in order to lead to a one-dimensional polymer for 1 and a two-dimensional polymer for 2. Density functional theory calculations provide useful informations on the involved orbitals on the 2-bridging iodide and on the structure of the systems, leading to a small H-I-H angle of 71.2° in 1 compared to a large H-I-H angle of 121.8° in 2.