  The term `solar tornadoes' has been used to describe apparently rotating
magnetic structures above the solar limb, as seen in high resolution images and
movies from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics
Observatory (SDO). These often form part of the larger magnetic structure of a
prominence, however the links between them remain unclear. Here we present
plasma diagnostics on a tornado-like structure and its surroundings, seen above
the limb by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard the
Hinode satellite. We aim to extend our view of the velocity patterns seen in
tornado-like structures with EIS to a wider range of temperatures and to
provide insight into the physical characteristics of the plasma. Using Gaussian
fitting to fit and de-blend the spectral lines seen by EIS, we calculated
line-of-sight velocities and non-thermal line widths. Along with information
from the CHIANTI database, we used line intensity ratios to calculate electron
densities at each pixel. Using a regularised inversion code we also calculated
the differential emission measure (DEM) at different locations in the
prominence. The split Doppler-shift pattern is found to be visible down to a
temperature of around log(T) = 6.0. At temperatures lower than this, the
pattern is unclear in this data set. We obtain an electron density of log(n_e)
= 8.5 when looking towards the centre of the tornado structure at a plasma
temperature of log(T) = 6.2, as compared to the surroundings of the tornado
structure where we find log(n_e) to be nearer 9. Non-thermal line widths show
broader profiles at the tornado location when compared to the surrounding
corona. We discuss the differential emission measure in both the tornado and
the prominence body, which suggests that there is more contribution in the
tornado at temperatures below log(T) = 6.0 than in the prominence.
