Kinetics of silver extraction from nitrate solutions with triisobutylphosphine sulfide dissolved in n-octane was studied. Experiments were carried out in a rotating diffusion cell. The rate constants of forward and reverse chemical reactions were evaluated : the former k(f)* = 1.064 x 10(-3) mg(9)/(mol(3) . s) and the latter k(r)* = 2.085 x 10(-1) s(-1). The value obtained for the activation energy shows that the process of silver extraction with triisobutylphosphine sulfide is a predominantly diffusion-controlled process.