Solubilization of solid lipids in oil-in-water microemulsion is an important step in the preparation of lipid nanoparticles. Oil in water microemulsion has been prepared using Tween-80 (T-80) as a surfactant and isopropyl myristate (IPM) as an oil phase with a view to utilize them for the preparation of Solid Lipid Nanoparticles (SLN). The microstructure of the microemulsions were evaluated using laser light scattering studies. From light scattering studies, it was observed that the intensity of scattered light increases on increasing the concentration of IPM at a fixed concentration of T-80 (15%), reflecting an increase in the size of the micelles. Dynamic light scattering studies show that the hydrodynamic diameter of the micelles increases on increasing the concentration of IPM. Phospholipon® 90 G (lipid) solubilized microemulsions were prepared using 1:1 w/w mixture of lipid and IPM as the oil phase. DLS studies suggest that addition of lipid did not alter the size of microemulsion droplets significantly.