An aqueous suspension of 1 wt.% laponite was investigated in terms of its rheology and hydrodynamic behaviour in a sudden expansion flow. The fluid was shear-thinning, thixotropic and had an yield stress which was measured by direct and indirect methods. The oscillatory tests showed that the elasticity of the 1% laponite suspension was very small. The high Reynolds number flow downstream of a sudden expansion, with fully-developed inlet conditions, showed no major difference in relation to the flow of water. There were no differences between the mean and turbulent flow characteristics of the water and laponite flows upstream and downstream of the expansion plane, except for a small anticipation of the loci of maximum Reynolds stresses with the suspension, which had no further consequence. In conclusion, the laponite suspension flows were akin to those of water.