The stoichiometric relation for the extraction of zirconium and hafnium from acidic nitrate solutions was investigated with Cyanex272. Extraction runs were carried out batch wise at ambient temperature in the acidic range from 0.1 to 2.5 M. The results showed that in the acid concentration range under study, the preferred mechanism for the extraction of zirconium and hafnium is salvation. In addition, the instability constants for zirconium and hafnium complexes with nitrate anion have had a significant effect on the extraction efficiency.