The extraction equilibrium of sodium ion with 25,27-bis(carboxymethoxy)-26,28-bis(carboxyprorx3xy)-5,11,17,23-tetrakis(l,l,3,3-tetramethvlbutyl)calix[4]-arene and 25,26,27,28-tetrakis(carboxymethoxy)-5,ll,17,23-tetrakis(l,l,3,3-tetramethylbutyl)calix[4]arene has been studied by means of 'H-NMR spectrometry. The extraction equilibria of copper (II) ion with the above extractants have also been investigated in the absence or presence of sodium ion to clarify the extraction mechanism and the effect of the coexisting sodium ion on copper ion.