A novel polymer material composed of cellulose triacetate as support, o-nitrophenyl octyl ether as plasticizer (solvent), and dicyclohexano-18-crown-6 as carrier was investigated as a solid extractant for metal ion sorption and as a membrane material for ion transport. Selective extraction and transport of Pb(II), Ga(III), and Fe(III) were observed. The influence of the source solution counterion on sorption and transport processes was investigated. The transport mechanism is discussed in terms of diffusion coefficients (D) and extraction constants (K-1). A diffusion-limited transport model has been found to accurately describe metal ion transport by dicyclohexano-18-crown-6 in these systems. The membranes are easy to prepare in the laboratory, and they may be useful in separation and concentration procedures.