HCl was recovered as an aq. soln. from its soins. in pure and waste H2SO4 by membrane distn. at 333 K and 343 K (feed) and 294 K (distillate) under lab. conditions. Com. capillary polypropylene membrane (surface 0.0112 m(2)) was used in the study. The salts-contg. waste H2SO4 was taken from TiO2 manufg. The process was carried out for 18-49 h. The resulting distillate was a pure hydrochloric acid (HCl content up to 46 g/dm(3)). Both H2SO4 and non-volatile salts totally remained on the feed side of the membrane.