We propose here a detailed study of the diffuse scattering of ferrocene with the key objective of investigating the origin of the cyclopentadienyl (Cp) ring disorder in this system. It is intended that the high quality diffuse scattering datasets collected over large volumes of reciprocal space will allow us to distinguish between the three likely ring disorder scenarios, namely: i) static statistical disorder, ii) Cp ring tunnelling and iii) continuous rotational disorder. To accomplish this goal, we intend to collect four high quality diffuse scattering datasets using a large single crystal sample of perdeuterated ferrocene for temperatures in the interval 180 K-350 K. To our knowledge, this will be the first such study of ferrocene, which we estimate will require 6 days of beamtime on SXD