Free Cl-2 etching of InP/In0.53Ga0.47As at high temperatures was investigated for the fabrication of nanostructures. The effects of Cl-2 flow rate, mask material, and substrate temperature on the sample etch rate, surface morphology, and etch profile are described. The etch profile is found to be temperature dependent for stripes along the crystal directions studied, namely, [110], [1(1) over bar0$], and [010]. The profile was affected by the choice of mask material among Ti and SiO2. The etch characteristics are found to be suitable for controlled etch of quantum wires. The etch technique is compatible with in situ etch and regrowth when SiO2 is used as the etch mask, since InP does not grow on SiO, sui-faces and allows selective regrowth immediately after etching. Quantum well wires (QWWs) with widths as low as 30 nm were fabricated using electron beam lithography and free-Cl-2 etching. Low temperature photoluminescence (PL) was used to characterize the QWWs. The normalized PL efficiency of narrow free-Cl-2 etched QWWs was found to be higher than that of ion-assisted dry-etched wires and comparable to that of wet-etched wires.