InP-based HEMT technology presents substantial performance advantages for millimeter wave applications such as high-speed wireless communications; radio astronomy; and radar. We report on the development of a 50-nm gate-length process for millimeter wave InP HEMTs. The gate patterns were defined using a single electron beam exposure and a bi-layer resist system. The process was evaluated on pseudomorphic InAlAs/InGaAs/InP HEMT material. A two-finger; 100 ¬Ķm gate-width device showed an extrinsic DC peak transconductance of 650 mS/mm at Vds = 1.0 V. At the same drain bias; the transit frequency and the maximum frequency of oscillation were 180 and 230 GHz respectively. The developed 50-nm process constitutes the new baseline for the InP MMIC process at the Microwave Electronics Laboratory at Chalmers.