Temperature‐dependent current‐voltage (I‐V) and capacitance‐voltage (C‐V) measurements reveal that a low but nonzero barrier is present at the interface of Al deposited on ultrahigh‐vacuum‐cleavedn‐InP (110), and that the true barrier height lies between 0.21–0.26 eV. An analysis which allows for the presence of trapped charge near the interface provides the most accurate and consistent determination of the effective barrier. The effective barrier is strongly and reversibly temperature dependent, corresponding to movement of the Fermi level with temperature. The trapped interfacial charge resides in acceptorlike electron traps 0.10 eV below the conduction‐band edge. The traps are distributed 100–200 A˚ into the space‐charge region. These results are discussed in terms of models of defect electrical activity at metal‐semiconductor interfaces, and are related to results of annealing studies.