Hybrid perovskites have potential applications in several electrochemical devices such as supercapacitors, batteries, and fuel cells. However, despite various potential applications, there have been limited studies on compounds containing Cd. Therefore, in this study, the structures and phase transition temperatures TC of organic–inorganic perovskite [NH3(CH2)nNH3]CdCl4 (n=2, 3, and 4) were confirmed by X-ray diffraction and DSC experiments. The thermal stabilities obtained by TGA and DTA results were considered as a function of the length n of the CH2 groups in the cation. In addition, structural characteristics and molecular dynamics of the cation and anion near TC were studied by 1H MAS NMR, 13C MAS NMR, 14N static NMR, and 113Cd MAS NMR experiments. From these results, regardless of whether n is even or odd, the differences in thermal and physical properties were minimal. Rather, the difference in molecular motion relative to the length of the cation was seen only at higher temperatures. These results provide insights into the thermal stability and molecular dynamics of [NH3(CH2)nNH3]CdCl4 crystals and are expected to facilitate potential applications.