The treatment of tanning wastewater was studied by means of reverse osmosis and ultrafiltration. Tests were carried out on laboratory scale using membranes of polyamide (reverse osmosis) and of polysulfone (ultrafiltration). The evaluation of the system was performed by chemical analysis, pH measurements and visible spectrophotometry. Effects of the protein contained in the industrial effluent, the applied pressure and the feed temperature on the permeate flux were analyzed. The polyamide membrane used allowed us to obtain permeates with a low chromium (III) content (7-10 mg/L) but with appreciable amounts of SO4- (1-3 g/l), Cl- (9-14 g/L) and Na+ (5-10 g/L). The presence of chromium (III) polymers was determined in the original effluent and in the concentrates obtained by reverse osmosis. Finally, it was established that during the operation of reverse osmosis, the transport of H+(H3O+) from the concentrate to the permeate was produced.