Reactive ion etching (RIE) of GaN has been performed using BCl3 and additives, Ar and N-2 to BCl3 plasma. The etch rate, surface roughness and the etch profile have been investigated. The etch rate of GaN is found to be 104 nm/min at rf power of 200 W, pressure of 2 Pa, with 9.5 seem flow rate of BCl3. The addition of 5 seem of Ar to 9.5 seem of BCl3 reduces the etch rate of GaN while the addition of N-2 does not influence the etch rate significantly. The RIE of GaN layer with BCl3/Ar and BCl3/N-2 results in a smoother surface compared to surfaces etched with BCl3 only. The etched side-wall in BCl3 plasma makes an angle of 60 degrees with the normal surface, and the angle of inclination is more in cases of BCl3/Ar and BCl3/N-2 plasmas. The RIE induced damage to the surface is measured qualitatively by PL measurements. It is observed that the damage to the etched surfaces is similar for all the plasmas.