Two solvent mixtures, namely, tetrahydrosylvanc-nitric acid (sp.gr.1.42)-ovater (85:10:5 v/v) and methyl acetate-nitric acid (sp.gr.1.42)-water (85:5:10, v/v), were suggested by Burstail et al.^[1] for the separation of lanthanidcs, scandium and thorium.With she latter mixture, the thorium formed a diffuse spot.It has been tried in this laboratory to remedy the said-drawback by varying the composition of the solvent systems.The Schleicher and Schurr 2045a paper was found to give better defined spots than the 2040a paper.The paper strips used were 1.5, 2.0 and 2.5 cm wide and 29 cm long.Throughout this work, the ascending technique was adopted.Saturated 90% alcoholic solution of alizarin was used to detect the elements studied.The composition of eluents (Nos.1 to 4).and the RF values of zirconium, lanthanides, scandium and thorium，when present singly or admixed, arc given in Table 1 (cf.Figure 1, chromatograms Nos.1-4).With eluent No.3 a well-defined thorium spot could be obtained.Increasing acidity of the eluting system does not affect the RF value of zirconium, but affects those of lanthanides and scandium slightly and increases that of thorium greatly.