a new process has been developed for production, by direct acetylation, of soluble cellulose acetates having degrees of substitution of 0. 9-2. 0 in dioxane with the use of large amounts of sulfuric acid. it was shown earlier that sulfuric acid, which is widely used as an acetylation catalyst, forms an equimolecular complex with acetic anhydride; this complex is fairly stable in acetic acid and methylene chloride. this complex is of particular interest in relation to development of a process for production of primary cellulose acetates in dioxane. experimental evidence indicates that the spectra of concentrated solutions of sulfuric acid dioxanate contain an absorption band corresponding to stretching vibrations of hydroxyl group with a peak at 24. 5 $multiplied by (times)$ 10**4 m** $minus$ **1, the position of which is independent of dilution; it can therefore be assumed that this band is also present in the spectrum of pure sulfuric acid dioxanate. it can be inferred from the investigation that the sulfuric acid-acetic anhydride complex in dioxane reacts with the latter to form a compound, presumably the ternary complex (ch//3co)//2o $multiplied by (times)$ h//2so//4 $multiplied by (times)$ c//4h//8o//2, existing in equilibrium with excess dioxane. 6 refs