Abstract: A process for the preparation of a chrome-tanning agent and Glauber's salt from sodium bisulphate contaminated with chromium compounds obtained as by-product from the manufacture of chromic acid from solid sodium dichromate and sulphuric acid, comprising(a) treating an about 20 to 70% aqueous sodium bisulphate solution which contains chromium compounds and is acid with sulphuric acid with sulphur dioxide until all the chromium is present in the form of chromium (III);(b) adding sodium hydroxide to the reduced solution until it has a pH of between about 4 and 5;(c) adding sodium carbonate to the solution to a pH of between approximately 8 and 8.5, thereby precipitating chromium (III) hydroxide;(d) separating off the precipitated chromium (III) hydroxide; and(e) evaporating the filtrate left after removal of the chromium (III) hydroxide to yield solid sodium sulphate.