Abstract: It has been shown that over 80% of the protactinium-231 remained in the residue, when the uranium ore concentrate was treated by 40% nitric acid with the addition of aluminium with A1/F = 2-4. The content of 231Pa is 1.47×10-7g per gram residue.A Process for the recovery of 231Pa from this residue with high yield is developed. It consists of the following stages;1. Leaching 231Pa from the residue with 2N HF.2. Extracting 231Pa from leaching liquor with phenyl (2-ethylhexyl) phosphonate -trialkylphosphine oxide-xylene (organic phase I) and stripping it from the extra-ctant with IN HF. 3. Extracting 231Pa from the first resultant aqueous phase with trialiphatic amine-mixed alcohol-kerosene (organic phase Ⅱ), washing the organic phase obtained with 9.6N HC1-0.5% H3BO3 and stripping 23lPa from the organic phase with 2N HC1-0.06N HF.4. Adjusting the acidity of the second resultant aqueous phase to 8N HCI, adding H3BO3 to complex F" and extracting 23IPa by organic phase Ⅱ.5. Washing organic phase with 7N HCl-6% H2C2O4 solution and re-extracting 231Pa from the extractant by 2N HC1-0.06N HF.6. Purifying 231Pa by chromatographic method at the final stages, adjusting the acidity of the third resultant aqueous phase to 8N HCI, adding aluminium on the A1/F = 10 and then passing the solution through a column filled with 100-200 mesh 201×7 macroreticular anion exchange resin in the Cl- form. 231Pa and Nb are absorbed on the resin, Zr and Ti are not retained. Nb is eluted with 8N HCl-2% H2C2O4, 231Pa--with 2N HC1-0.06N HF.High purity of the protactinium fraction is obtained with the present procedure. The content of 231Pa in the eluate is 9 g/1, the total concentration of Zr, Nb and Ti is less then 1×10-2 g/1.