The results of studying the possibility of the most complete nickel and cobalt recovery during the hydrometallurgical processing of reduced ferriferous oxidized nickel (limonite) ore by weak solutions of sulfuric acid are presented. The ammonium complexing agent (NH4)(2)SO4 is used to enhance the selectivity of nickel and cobalt dissolution from a cinder. The cinder is leached at 90 degrees C for 2 and 4 h under atmospheric pressure with the pH of the solution varied in a range of 3.0-4.0.