The temperature-dependent characteristics of an InAlAs/InGaAs metamorphic high electron mobility transistor with an electroless plating (EP) Pd-gate metal are studied and demonstrated. Under the low-temperature and low-energy chemical deposition conditions, the EP deposition approach could reduce the thermal damage and disordered states to form an oxide-free metal-semiconductor interface. Therefore, good experimental results including the improved characteristics of forward voltage, reverse leakage current, Schottky barrier height, ideality factor, transconductance, and drain saturation current are found for a 1 mu m gate-length device. Moreover, the benefits of simplified process and low-cost show the promise of the proposed EP approach for III-V electronic applications. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.021202esl] All rights reserved.