A Microsponge delivery system (MDS) is “Patented, highly cross-linked, porous, polymeric microspheres polymeric system consisting of porous microspheres that can entrap wide range of actives. It is a unique technology for the controlled release consists of micro porous beads, typically 10-25 microns in diameter, loaded with active agent. Aceclofenac belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking the action of cyclooxygenase. The pharmacokinetic profile and intracellular metabolism of Aceclofenac provide a strong rationale for the development of a sustained release formulation. A Microsponge based drug delivery system of Aceclofenac was planned for development and characterization for in vitro performances. The effect of Eudragit RS100 and PVA on formulation of microsponges was determined by using 32 factorial design. Aceclofenac Microsponge were prepared using an Quasi emulsion solvent diffusion method by adding an organic internal phase containing Aceclofenac, Eudragit RS100, Tri ethyl citrate and solvent into a stirred aqueous phase containing polyvinyl alcohol.