Six commercially available glutaraldehydes were tested spectrophotometrically for their purity. These results were compared with glutaraldehyde purified by two experimental techniques. Ten sets of storage conditions were chosen and aliquots of purified glutaraldehyde were stored under these conditions for eight months. These samples enabled the reappearance of the main contaminant, absorbing strongly at 235 nm, to be examined with regard to temperature, light and the availability of oxygen. From the results the optimum criteria for storage of pure glutaraldehyde were elucidated. The results lend weight to the view that the main contaminent in stored glutaraldehyde is a polymer of glutaraldehyde and not glutaric acid.