AbstractThe influence of confinement on the ionic liquid crystal (ILC) [C18C1Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si‐based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid‐to‐liquid‐crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid‐crystalline‐to‐liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid‐to‐liquid‐crystalline phase transition observed for the neat ILC. For applications within the “supported ionic liquid phase (SILP)” concept, the experiments show that in pores of diameter 50 nm a pore filling of α>0.4 is sufficient to reproduce the phase transitions of the neat ILC.