A series of the layered tin-iodide perovskite compounds with a general formula (RNH3)(2)SnI4 have been prepared. The RNH3 species adopted are normal-alkyl ammonium, cyclic-alkylammonium, and phenylethylammonium, and as the (RNH3)(2) unit alkyldiammonium is adopted. The obtained single crystals have been subjected to X-ray diffraction experiments. The structures of the SnI42- layers, their bond lengths and angles, are widely varied depending on the cationic organic species between the perovskite layers.