4-Tert-butyl-2-(α-methylbenzyl) phenol(t-BAMBP) was used in cyclohexane in the extraction of rubidium from brine sources containing lithium. The effect of t-BAMBP concentration and aqueous phase p H on the rubidium and lithium extraction equilibrium was studied. t-BAMBP/cyclohexane was ef ficient and selective for rubidium extraction with optimal operating conditions being p H of 13.0 and initial t-BAMBP concentration of1.0 mol·L-1. The stoichiometry of the complex of t-BAMBP with rubidium is 4:1. The apparent extraction equilibrium constant of rubidium was calculated by fitting the experimental data. 4-Tert-butyl-2- (α-methylbenzyl) phenol (t-BAMBP) was used in cyclohexane in the extraction of rubidium from brine sources containing lithium. The effect of t-BAMBP concentration and aqueous phase p H on the rubidium and lithium-extraction equilibrium was studied. t-BAMBP / cyclohexane was ef ficient and selective for rubidium extraction with optimal operating conditions being p H of 13.0 and initial t-BAMBP concentration of 1.0 mol·L -1. The stoichiometry of the complex of t -BAMBP with rubidium is 4: 1. The apparent extraction equilibrium constant of rubidium was calculated by fitting the experimental data.