The hydrogenation and isomerization of 1-butene and cis-2-butene molecules are studied on platinum foil and single crystal (111), (100), and the stepped (755) surfaces at 300-350 K. In the presence of hydrogen, 1-butene and cis-2-butene are hydrogenated to butane. In addition, 1-butene is isomerized to cis-and trans-2-butenes, while cis-2-butene is converted to trans-2-butene. With a hydrogen pressure between 7 and 500 Torr, and a butene pressure of 3.5-70 Torr, both butene hydrogenation and isomerization rates exhibit a near-first-order dependence on the hydrogen pressure and a zero-order dependence on the hydrocarbon pressures. For both 1-butene and cis-2-butene molecules, the hydrogenation rates are insensitive to surface structures. The isomerization rate, however, is doubled for cis-2-butene molecules on the stepped platinum surface (Pt(755)).