The separation of niobium and tantalum and of noble metals by reversed-phase thinlayer chromatography has been studied.It is carried out on silica gel layers of 0.5 mm thickness supported by glass plates.Before chromatography,the silica gel layer as well as the paper strips are treated with 20 per cent tributyl phosphate benzene solution.Niobium can be separated from tantalum by reversed-phase paper chromatography and thin-layer chromatography both with ammonium thiocyanate: 10% oxalic acid:6 N hydrochloric acid(1.5:15:15; W/V/V) as the mobile phase.The R_f value for niobium and tantalum is 0.84 and 0.13 respectively with the former technique,and 0.82 and 0.02,by the latter.Rhodium-ruthenium-palladium-gold mixtures can be separated from one another also by reversed-phase thin-layer chromatography with 2 N hydrochloric acid as eluent.The R_f value for the metals mentioned is 0.95-1.0,0.18-0.43,0.70-0.84,and 0.00 respectively.