Abstract Dibenzo-18-crown-6 and formaldehyde polycondensate (PDBCO, M w = 6760, soluble in CHCl 3 and in 2-methyl-1-pyrolidone (NMP) was synthesized by condensation in NMP using formic acid as catalyst. Alternatively, a sequence of reaction steps, involving sodium bromide salts, for solubilization (see Scheme 1) was worked up. PDBC as its sodium bromide complex is compatible with polysulfone derivatives. PDBC was found to be active in KSCN transport across a liquid membrane. Membranes cast from PDBC were also compared in adsorption of anionic proteins (PGT) with sulfonated polysulfone (SPS) or aminated polysulfone (APS). The absorption of PGT on PDBC membrane is strongest, but reversible. Thermal decomplexation of the cations neutralizes the cation-charged membrane and causes elution of the anionic PGT polymer.