Extraction equilibria in the system aqueous solution of sulfuric acid-solution of trialkylamine (TAA) in a mixture of dearomatized kerosene and n-octanol-1 were measured at 25 degrees C in a broad range of acid concentrations. The effects of variation of solvent composition, as well as of sodium sulfate addition to the aqueous phase, were investigated. A mathematical model and computation algorithm were developed for correlation and simulation of experimental data. Simultaneous formation of three complexes (normal sulfate, hydrogen sulfate of TAA, and the dimer of the latter), as well as nonidealities in both phases, was included. The experimental data were successfully correlated, and participation of individual complexes on the total loading of amine was simulated. Data on sulfuric acid extraction with tri-n-octylamine in benzene by Alien were also correlated with the model and compared with the results of extraction with TAA in the mixed diluent.