We have performed photoemission experiments, using a tunable soft x-ray synchrotron radiation source to study the chemical changes of oxidized GaAs and AlAs surfaces subject to exposure from hydrogen ions. Results indicate that the net effects for hydrogen ion irradiation are (i) the reduction of arsenic and (ii) the growth Of the cation oxide components. The reduction of arsenic can result from the formation/desorption of arsine. The oxide overlayer after hydrogen ion treatments is dominated by cation oxides which are the more stable chemical species as described in the phase diagram. This oxide layer should then remain stable in atmosphere. These results can provide insight into the chemical reaction between hydrogen ions and oxidized AlGaAs surfaces.