The family of hybrid Prussian blue analogues includes many electroactive materials, where organic cations moving within the pores of the cyanide framework cause unusual and exploitable electrical properties. Our target material, (HIm)2K[Fe(CN)6], undergoes a phase transition associated with a dramatic decrease in dielectric constant on cooling, as the imidazolium ions stop rotating and freeze into position. The local dynamics in the high-temperature phases remain poorly understood; but it is precisely these that we will need to control in order to engineer new materials in this family with desirable properties. We therefore propose to measure the nuclear momentum distribution for each element in this sample via DINS measurements on VESUVIO. Our results will help to elucidate the link between the motion of the imidazolium cations and the material's dielectric switching.