Competitive interactions of sulfhydryl compounds and quinone derivatives with poly(4-vinylpyridine) gels have been studied in organic solvents. 7,7,8,8-Tetracyanoquinodimethane (TCNQ) oxidizes a sulfhydryl compound to disulfide, while TCNQ is reduced to an anion radical that reacts with the gels. Adsorption of long-chain sulfhydryl compounds onto gels causes the gel swelling, whereas oxidation of the adsorbed sulfhydryl compound to disulfide by TCNQ, and therefore, its removal from the gel results in the gel shrinking. The larger the highest occupied molecular orbital energy of the sulfhydryl compound, the stronger its interaction with a quinone derivative and thus the faster the removal from the gels, as revealed by HPLC.