A new carboxylic acid extractant containing a sulfur atom, α-butylthiolauric acid(abbreviated as α-BTLA) was synthesized to investigate the extraction equilibrium of silver(I) from 1 mol/dm3aqueous ammonium nitrate solution with its toluene solution at 30°C. Moreover, the extraction of silver(I) with palmitic acid in toluene was studied to compare with the extraction properties of α-BTLA. It was found that silver(I) is extracted as AgR×3HR for both carboxylic acids(HR) according to the following equation.