A ferrofluid on diester base containing ultrafine magnetite particles has been investigated by means of Mössbauer spectroscopy in the temperature range from 77 K to 300 K. Superparamagnetic relaxations and translational diffusion have been found to be the predominating dynamic processes. A slowing down of the superparamagnetic relaxations in the liquid phase compared with frozen material points to a local ordering. The measured diffusion coefficient is in satisfactory agreement with the theory, if a slip of the fluid flow at the particle surface is assumed