Extraction of As(III) and As(V) from sulphuric acids solutions of H2SO4 of various concentration (50–200 g/dm3 with Cyanex 923 dissolved in Exxsol 220/230 (50% v/v) was studied and compared. Cyanex 923 can be considered as an effective arsenic extractant. Sulphuric acid is co-extracted. Extraction both of As(III) and As(V) occurs quickly and the equilibrium is obtained after 5 minutes. The isotherms of As(III) and As(V) extraction at various sulphuric acid concentrations were determined and used to model the multistage countercurrent process. Arsenic can be stripped with water.