Three　polymorphs　of　Ga2O3　(α-,　β-,　and　γ-Ga2O3)　were　prepared,　and　their　photocatalytic　activities　were　evaluated　by　the　decomposition　of　volatile　aromatic　compounds　(e.g.,　benzene,　toluene,　and　ethylbenzene)　in　dry　air　stream　under　UV　light　illumination　at　room　temperature.　It　was　found　that　the　Ga2O3　catalysts　exhibited　much　higher　photocatalytic　activity　than　commercial　TiO2.　The　photocatalytic　activities　of　the　Ga2O3　polymorphs　were　strongly　influenced　by　their　crystal　structure,　and　their　specific　activities　decreased　in　the　following　order:　β-Ga2O3　＞　α-Ga2O3　＞　γ-Ga2O3.　The　reasons　for　the　differences　in　photocatalytic　activity　of　the　Ga2O3　polymorphs　are　discussed　in　terms　of　crystallinity,　geometric　structure,　and　electronic　properties　of　the　polymorphs.　©　2007　Elsevier　Inc.　All　rights　reserved.