Spreading of a nano-fluid comprising nano-sized particles and a solvent on solids has significant technological applications. The confinement of nano–fluid inside the three phase contact region (wedge film) can result in highly ordered particle structure formation (Nature, 423, 156-159, 2003). This ordering gives rise to the structural component of disjoining pressure and facilitates the spreading of the nano-fluid. Experiments were conducted using an oil drop on a glass surface submerged in a nano-fluid. The contact line movement of the wedge film was monitored by using a high resolution light interferometry technique. We systematically investigated the effect of drop size (capillary pressure) and nano-particle volume fraction on the rate of movement of the inner three-phase contact line. The experimental results were modeled using lubrication theory which accounts for the disjoining pressure. At high particle volume fraction, the spreading rate is dominated by the disjoining pressure gradient, while at lower concentrations the effects of the capillary and hydrostatic pressure are more pronounced.