The molar ratios of Th:BFCA of 1:5000 for p-SCN-Bn-DOTA and 1:100 for p-SCN-Bn-DTPA were found to be optimal and resulted in 86-90% RCY for both BFCAs complexes. Thorium-234 incorporation into both radioimmunoconjugates reached 45-50%. It has been shown that Th-DTPA-Nimotuzumab radioimmunoconjugate specifically bound with EGFR overexpressing epidermoid carcinoma A431 cells.