This paper discusses the surface topography and compositional change of the surfaces of cesium-ion-bombarded Si, GaAs and InP. Microtopographies of ∼0.1 µm are observed in all of these samples, even in the early stage of sputtering. Microtopographies are formed through oxidation of the cesium-containing surface in air. In compound semiconductors, the altered layer formed by preferential sputtering plays an important role in microtopography development. Especially in InP, microtopography is observed under both argon and oxygen ion bombardments as well as under cesium-ion bombardment. The high vapor pressure of phosphorus is thought to be responsible for the formation of the altered layer.