Five diglycolamide-appended calixarene (C4DGA) ligands, viz. C4DGA with no substituent (L-I), n-propyl (L-II), 3-pentyl (L-III), n-octyl (L-IV) and both side (L-V) substituents were evaluated for the separation of carrier free 90Y from a 90Y–90Sr mixture using the flat sheet supported liquid membrane technique. Based on the results of earlier batch studies, the transport properties of the C4DGA ligands towards Y(III) and Sr(II) were monitored at two different feed acidities. The transport rates were significantly lower for 6 M HNO3 as compared to 3 M HNO3 as the feed. After 6 h, the observed trend of Y(III) transport with the C4DGA ligands using a feed of 3 M HNO3 was: L-I ~ L-III > L-V > L-IV > L-II which changed to L-III > L-I > L-IV > L-V > L-II for 6 M HNO3 as the feed. With 3 M HNO3 as feed, >97% Y(III) transport was obtained with L-I and L-III in 6 h. Comparative Sr(II) transport was negligible resulting in high decontamination factors. In a one-step separation process, using L-I as the carrier ligand, pure 90Y was obtained as the respective complex with either EDTA or DOTA. The highlights of this liquid membrane-based separation method comprise: its easiness, one-step separation, low ligand inventory, relatively pure product and continuous method.