Eleven polymers were used to produce coatings (2-20 nm) on the surface of an aluminum powder to modify its properties. The polymers studied are polyisobutylene (PIB), poly (vinylidene fluoride) (PVF), poly (methyl methacrylate) (PMMA), polystyrene (PS), poly(ethylene terephthalate) (PETP), poly(4-vinylbiphenyl) (PVB), poly(4-vinylpyridine) (PVP), poly(4-bromo styrene) (PBS), poly (vinylidene fluorideco-hexafluoropropylene) (PVFH), poly (styrene-co-methyl methacrylate) (PSMMA), poly (vinyl chloride-co-vinyl acetate) (PVCVA). Supercritical carbon dioxide was used as a solvent and as a transport medium. Coated aluminum powders exhibit enhanced resistance to the dissolution in basic solutions. The protective properties of the polymeric films were quantified based on the dissolution rate. Polymeric films that contain aromatic rings were characterized using UV absorption spectrophotometry. Temperature and pressure were varied over 84 - 210 OC and 80 -480 atm to determine the optimal condition for coating. A technique to measure the solubilities of poorly soluble polymers in supercritical carbon dioxide was developed. The solubility of PVB is determined as 11.7 mg/L at T = 170°C and p = 341 atm. The study of the morphology of the coated powder was carried on by using an Environmental Scanning Electron Microscope (ESEM) and an Electron-Dispersive Xray Detector (EDX). The coatings produced using supercritical carbon dioxide as well as using organic solvents were compared and evaluated.