The　photocatalytic　behavior　of　catalysts　is　closely　related　to　their　surface　properties.　Here,　the　K4Nb6O17　nanolayered　photocatalyst　was　synthesized　by　the　hydrothermal　method　and　was　subsequently　surface-modified　by　being　loaded　with　ultrafine　gold　nanoparticles　via　the　decomposition　of　a　gold　cationic　complex　precursor　[Au(en)　2]3+　(en　=　ethylenediamine).　The　photocatalytic　activities　of　the　as-synthesized　samples　were　evaluated　in　the　photodegradation　of　the　azo-dye　methyl　orange　(MO)　under　UV　irradiation.　The　photocatalytic　activity　of　the　pristine　nanocrystalline　K4Nb6O17　sample　was　efficiently　improved　as　the　initial　solution　pH　was　decreased;　however,　the　photocatalytic　activity　was　diminished　when　the　concentration　of　dissolved　oxygen　was　decreased.　This　behavior　indicates　that　a　synergistic　effect　of　the　dissolved　oxygen　molecules　and　surface　bridging　hydroxyl　groups　plays　a　key　role　in　the　photocatalysis.　In　addition,　we　found　that　an　appropriate　surface　modification　of　the　K4Nb6O17　by　Au　nanoparticles　can　significantly　enhance　its　photocatalytic　activity,　an　effect　which　may　be　attributed　to　the　efficient　separation　of　photogenerated　charge　carriers　in　this　nanocomposite　system.　©　2013　Elsevier　B.V.