26, 28-(Dibutylcarbamoyl) methoxy-5, 11, 17, 23-tert-butylcalix [4] arene and two geometric isomers of 27, 28-(dibutylcarbamoyl) methoxy-5, 11, 17, 23-tert-butylcalix [4] arene have been used to extract UVI, MoVI, CrVI and SeVI from aqueous solution into toluene or isooctane.