Many hybrid Prussian blue analogues show exploitable electric behaviour, such as piezo-, pyro-, or ferroelectricity or dielectric switching. We have previously characterised one such material, (HIm)2K[Fe(CN)6], by QENS: this is an ideal technique to reveal the dynamics of the imidazolium cation rotating in the pores, since the only hydrogen in the material is in this cation. We now propose to measure the analogous material (HIm)2K[Co(CN)6] in the same way. Although the Fe and Co compounds are isostructural, their phase behaviour differs in subtle but significant ways. Understanding the link between the structural phase transitions and the cation dynamics revealed by our proposed experiment will help to crystal engineer materials with targeted dynamic behaviour, and hence desirable electric functionality.