The present invention discloses a process for synthesizing a hydrogenated polymer that comprises: (1) preparing a aqueous polymerization medium which is comprised of (a) at least one monomer, (b) a polymerization control agent, and an emulsifier, wherein the emulsifier is prepared in-situ within the aqueous polymerization medium; (2) initiating polymerization of said monomer within the aqueous polymerization medium to produce a latex of an unsaturated polymer; (3) treating the latex of the unsaturated polymer with (a) an oxidant selected from the group consisting of oxygen, air and hydroperoxides; (b) a reducing agent selected from the group consisting of hydrazine and hydrates of hydrazine; and (c) a metal ion activator to produce the hydrogenated polymer. The present invention further discloses a process for synthesizing a hydrogenated polymer that comprises: (1) preparing a monomer solution which is comprised of (a) at least one monomer, (b) a conjugate acid of a surfactant with a pK.sub.a of less than about 14, and (c) a controlled free radical polymerization agent; (2) preparing an aqueous medium which is comprised of (a) water, and (b) a conjugate base of a weak acid wherein the pK.sub.b of the base is less than about 14; and (3) mixing the monomer solution with the aqueous medium under conditions that result in the in-situ formation of an emulsifier; (4) initiating free radical polymerization to produce a latex of an unsaturated polymer; and (5) treating the latex of the unsaturated polymer with (a) an oxidant selected from the group consisting of oxygen, air and hydroperoxides; (b) a reducing agent selected from the group consisting of hydrazine and hydrates of hydrazine; and (c) a metal ion activator to produce the hydrogenated polymer.