Liquid-liquid extractions of zirconium/IV/, thorium/IV/ and uranium/VI/ with a tetradentate Schiff base, bis/salicylidene/ ethylenediamine /H2Salen/ in benzene as the diluent have been studied. Comparison of such results with those in case of a bidentate Schiff base, N-salicylidene-p-toluidine /HSalTol/ shows that the extraction of UO
is significantly improved if H2Salen is used instead of HSalTol2. A single extraction at pH 6.5 with H2Salen removes uranium/VI/. Extraction of all the three metals becomes quantitative at pH 6.5. The extracted species, which have been derived from slope-analyses of extraction results, seem to be of the type [Zr4/OH/12 /HSalen/2]Cl2, [UO2/OH/ /HSalen/] and [Th/OH/3 /HSalen/].