The complexation processes between K+, Na+ and NH4+ cations with macrocyclic ligand, 4\\\'-nitrobenzo-15C5, were studied in acetonitrile-methanol (AN-MEOH) binary mixtures at different temperatures using conductometric method, the conductance data show that the stoichiometry of the complexes formed between the ligand and K+, Na+ and NH4+ cations is 1:1(M:L) for the case of K+, Na+ cations, addition of 4\\\'-nitrobenzo-15C5 to these cations solution, causes a continuous increase in the molar conductivities which indicates the mobility of the complexed cations is more than the uncomplexed ones. The values of stability constants of the complexes were determined from conductometric data using GENPLOT computer program. The obtained results show that the formation constants of complexes changes with the nature and composition of the binary mixed solvent. The values of thermodynamic parameters (DH 0C, DS 0C) for formation of the complexes were obtained from temperature dependence of the formation constants and using the vant’Hoff plot. The results show that the complexes are entropy stabilized and in some cases the complexation reaction are endothermic, but in certain cases are exothermic.

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