Co-transport of metals (Hg2+, Pb2+, Na+) from an aqueous solution into an aqueous-receiving solution through a bulk liquid membrane containing calix[4]arene nitrile derivatives as carriers was investigated. Kinetic parameters were analyzed with consecutive irreversible first-order reactions and the effect of solvents such as CH2Cl2, CHCl3, and CCl4 was also examined. The transport rates show that both nitrile derivatives are efficient and selective for Hor(II) ions with respect to Na+ and Pb2+ ions and the dinitrile derivative is found to be a better carrier than the tetranitrile one. The membrane entrance- and exit rate-constants depend on the solvent type and are found to be in the order CH2Cl2 > CHCl3 > CCl4. A remarkable difference was also observed of the same order for fluxes.