Interaction of the water-soluble platinum and palladium coproporphyrins with cationic carriers, DEAE-dextran and CTAB, was investigated in aqueous solution by optical spectroscopy including pH-dependences of the absorption and emission spectra. In addition, solid-state coatings of the complexes were prepared on solid supports and their phosphorescent properties were studied. Contrary to the pure dyes, in the dry and solid state, the complexes strongly phosphoresce in air, are weakly quenchable by air oxygen, but are sensitive to the water content in their environment. Their applicability to quenched-phosphorescence sensing was discussed and compared to that of the phosphorescent polymer film compositions and Langmuir-Blodgett coatings.