H@sub 2@S attacks iron aggressively and causes the formation of iron sulfide. The sulfidation process is more kinetically favorable than other processes such as carburization. We are interested in determining a way to chemically pretreat iron surfaces to improve resistance to H@sub 2@S. One strategy is to alloy the surface. Here we investigate whether alloying an Fe surface with Al or Si might improve such resistance, via periodic density functional theory calculations of H@sub 2@S adsorption and dissociation on low-index surfaces of the intermetallic compounds FeAl and Fe@sub 3@Si. Stable adsorption structures and relative stabilities of H, S, HS, and H@sub 2@S on FeAl(110), FeAl(100), Fe@sub 3@Si(110), and Fe@sub 3@Si(100) are elucidated and compared with those on Fe(110) and Fe(100). We also present predicted minimum energy paths and energy barriers for the sequential dehydrogenation steps: H@sub 2@S to HS + H and HS to H + S. Our study shows that FeAl is indeed more resistant to H@sub 2@S attack than Fe, while Fe@sub 3@Si is as susceptible as Fe.