The separation behavior of ⁹⁰Y from ⁹⁰Sr was investigated by diluents variation using solvent extraction and supported liquid membrane techniques employing N,N,N′,N′-tetra-2-ethylhexyldiglycolamide (T2EHDGA) as the extract ant. Both D_Y (distribution ratio of Y(III)) and S.F.(separation factor) were found to be high in the solvent extraction studies when chloroform was used as the diluent. Subsequent supported liquid membrane (SLM) studies using PTFE flat sheet membranes containing 0.2 MT2EHDGA in various diluents indicated the trend of Y transport as xylene> hexone > chloroform > carbon tetrachloride >n-dodecane + 30% iso-decanol mixture. However, the Sr(II) transportrates were also high with xylene, hexone, and carbon tetrachloride as the diluents which led us to carry out subsequent studies using chloroform and n-dodecane +30% iso-decanol mixture. Acid variation studies in chloro- form system indicated an interesting phenomen a of increasing Y(III) transport and decreasing Sr(II) transport with increasing acid concentration. Separation of ⁹⁰Y from a mixture of ⁹⁰Sr and ⁹⁰Y was also attempted.