Surface properties of GaAs (001) cleaned with H3PO4 or HCl solutions and passivated with (NH4)(2)S-x solution were analyzed using Xray photoelectron spectroscopy. All of the treatments were carried out in a glove box under a nitrogen-controlled atmosphere. Every cleaning process produced elemental As with a 42.0 eV photoelectron binding energy. The generated elemental As increased with the etching capability of acid to GaAs and the cycling order of applying acid to GaAs. Successive sulfidation treatment resulted in the formation of an As-S bond with a 42.8 eV photoelectron binding energy. And the observed quantity of As-S bond was closely related to the elemental As concentration. Photoluminescent experiments showed that improvement of surface properties in sulfidation treated GaAs (001) mainly depends on the number of sulfur bonds.