Extremely smooth GaAs surfaces are attained after SiCl4reactive ion etching by preparing the surface before etching with hydrogen plasma exposure to selectively remove the native surface oxides. Using this hydrogen plasma pretreatment, the surface morphology after etching is equivalent to that of the original surface since the etching proceeds uniformly through the GaAs without micromasking effects from a nonuniform surface oxide. The beneficial effects of the hydrogen plasma processing are observed in two different reactors and are found to be independent of the platen temperature during etching. Using atomic force microscopy we find an optimized hydrogen plasma process produces an etched surface morphology with an average surface roughness of 0.9–1.5 nm, as compared to the surface roughness of 0.6 nm before etching or as great as 11.8 nm after etching without the hydrogen plasma pretreatment.