The optical potential is investigated for a chemically reactive system, K + CH3I, with an assumed potential of interaction among the three species, K, I, CH3. The complex optical potential satisfies an integral equation with a kernel related to the solution of the three-body problem, as given by Faddeev. In order to obtain some information on the form of the optical potential without numerical analysis we introduce a number of approximations. The imaginary part of the optical potential, which gives rise to absorption (reactive and inelastic collisions), is with these approximations essentially a delta function of the K + CH3I distance. The real part of the optical potential is similar in form to the repulsive potential estimated from elastic scattering experiments on this system.