The aim of research is to enhance the solubility of crystalline gefitinib (GF), a poorly water-soluble drug, by developing drug delivery systems using chitosan oligosaccharide (COS) particle engineering. Fabrication utilizes ionic gelation followed by spray drying. The preliminary evaluations such as Uv-Vis, FTIR, DSC followed by advanced techniques like SEM and invitro drug release characteristics was performed along with solubility study. The spray-dried particles measured a mean diameter of 3.18 +/- 0.5 microns, %EE as well as load w/w improved from 63.25 +/- 2.1% and 37.98 +/- 1.5% w/w (COS nanoparticles) to 78.15 +/- 2.6% and 45.34 +/- 1.6% w/w (engineered microparticles), respectively. The zeta potential and in vitro studies demonstrated 41 +/- 3.5 mV and 92 +/- 2.1% (w/w) release suggest long-term stability and prolonged release. This novel engineering approach effectively enhances GF solubility and surface characteristics, offering promising potential for improving delivery characteristics.