We extend the Zamolodchikov-Faddeev algebra for the superstring sigma model on AdS 5 × S 5, which was formulated by Arutyunov, Frolov and Zamaklar, to the case of open strings attached to maximal giant gravitons, which was recently considered by Hofman and Maldacena. We obtain boundary S-matrices which satisfy the standard boundary Yang-Baxter equation.