The phenomenon of joint solubilization of proteins and polymers in organic solvents through complexation with Lithium salt is described. Proteins undergo solubilization in LiBr-containing tetrahydrofuran (THF) with the formation of mixed aggregates between protein and LiBr. It is suggested that the complexation of proteins with Lithium salt is reversible and protein can be recovered unchanged upon simple dissolution of its complex with the salt in water. Halogenated polymers, poly(ortho ester), and polyurethanes form optically clear phases with the insulin-ii complex in THF or dimethylformamide, whereas polysaccharides and poly(p-phenyleneterephthalamide) are miscible with proteins in the LiCl-containing dimethylacetamide.