For the first time, pore formation on n-InP(100) has been carried out by galvanostatic treatments in acidic liquid ammonia at 223 K. Voltage oscillations correlated to a specific current line oriented pore morphology have been evidenced by scanning electron microscopy. Whatever the anodic charge, a constant pore depth was formed (2-3 mu m). Porous layers have been characterized by ex situ photoluminescence measurements that have revealed a dead layer behavior. This work demonstrates the crucial role of interfacial phenomena illustrated by the use of this uncommon nonaqueous electrolyte. (c) 2007 The Electrochemical Society.