Abstract: A process for preparing manganese sulfate solutions having reduced concentrations of potassium impurity is disclosed wherein a digestion mixture of a reduced manganese ore, a source of water soluble aluminum ions, a source of water soluble ferric ions and an aqueous acid solution is prepared, having a solution pH ranging from about 0.5 to about 3.5. The mixture is then digested at a temperature sufficient to produce a mixed digestion product comprising a liquid phase of a manganese sulfate solution and a solid phase of digested ore residue and a particulate complex salt by-product. The liquid phase of manganese sulfate solution is then recovered from the mixed digestion product. An additional feature of this process involves conducting the digestion of the digestion mixture in the presence of at least one complex salt of the general formula:MFe.sub.n Al.sub.3-n (SO.sub.4).sub.2 (OH).sub.6where M is Na.sup.+, K.sup.+ or NH.sub.4.sup.+ and n is a number ranging from about 1 to about 3.