This invention relates to a composition, and method of forming said composition, for the controlled release of interferon. The controlled release composition of this invention comprises a biocompatible polymer and particles of metal cation-stabilized interferon, wherein the particles are dispersed within the biocompatible polymer. The method of the invention, for producing a composition for the controlled release of interferon, includes dissolving a polymer in a polymer solvent to form a polymer solution, dispersing particles of metal cation stabilized-interferon particles in the polymer solution, and then solidifying the polymer to form a polymeric matrix containing a dispersion of the interferon particles.