This paper reports a study of the etching properties of citric acid/hydrogen peroxide solution on InGaAlAs and GaAsSb. All data presented here show a trade-off between etching selectivity and roughness of the etched surfaces. The optimal volume ratio of the etchant is found to be 2:1 yielding, respectively, a selectivity of 33 and a roughness of R-rms 0.3 nm. An increase of volume ratio beyond the optimal value increases the surface roughness, while a decrease leads to decreasing selectivity. The surfaces etched using optimal volume ratio exhibit a high surface stability even after several days of exposure in air. (c) 2005 The Electrochemical Society.