The addition of nanoparticles to an organic ionic plastic crystal can result in orders of magnitude increases in ionic conductivity, which makes these materials of interest as solid state electrolytes. However, this effect is not universal and depends on both the nature of the organic ionic plastic crystal and on the type of nanoparticle used. The effect of addition of TiO2, Al2O3 and SiO2 nanoparticles to a range of ionic materials with varying plasticity and rotator phase behaviour has been studied by thermal analysis and conductivity and the effect on the different materials is compared.