The volumetric determination of manganese with 8-hydroxy-quinoline was investigated. Errors due to adsorption have been shown to increase with increase in (a) amount of excess reagent and (b) strong ammonia; and to decrease in presence of sodium chloride. The direct titration method was found to yield satisfactory results provided a large excess of oxine or ammonia was not used. The back titration method was found to yield very high values due to adsorption.