Using molecular dynamics simulations the transport properties of a model nanoparticle in solution are studied. In bulk solvent the translational diffusion coefficients are in good agreement with previous simulation and experimental work, while the rotational diffusion is more rapid than in previous simulations. When the nanoparticle is adsorbed at a liquid–liquid interface it becomes strongly attached to the interface. This leads to highly anisotropic motion with in-plane diffusion being several orders of magnitude larger than out-of-plane diffusion. By contrast the rotational diffusion is only slightly changed when the particle is adsorbed at the interface.