Metal-insulator-semiconductor (MIS) structures were produced by electron-beam deposition of Al2O3 on InP. The electrical properties of such structures were investigated. For optimum conditions, capacitance/voltage (C/V) measurements show that the interface state density can be reduced to 1011 states cm-2 eV-1 by heat treatments. Capacitance transient measurements lead to an estimate of 2×103 cm sec-1 for the surface recombination velocity.