In situ crystallization on the diffractometer of 1,1,1,3,3,3hexafluoro-2-propanol (HFIP) with and without pyridine allows to obtain the new polymorphic form II of HFIP and the cocrystal HFIPpyridine. In contrast of the known HFIP form I, single-crystal X-ray diffraction analysis of HFIP form II shows a reduced number of mol-683 ecules in the asymmetric unit (form I: ZЈ = 8, form II: ZЈ = 4) Furthermore, UNI Force Field calculations were used to gain a deeper understanding of the intermolecular potentials of the main interactions of the described crystal structures.