Abstract: The study aims to compute the enhancement factor (E) of the absorption of H2S by aqueous Fe2(SO4)3 solution with second order irreversible chemical reaction at isothermal condition. The study was conducted theoretically simulation program. The value of E was computed based on the derivation of the basic equation of film model absorption, and then the non linear film theory equations are solved numerically using orthogonal collocation method under MATLAB program.