Lanthanum　and　nitrogen　co-doped　SrTiO3　was　prepared　by　a　mechanochemical　reaction　method　using　SrTiO3,　urea　and　La2O3　as　the　raw　materials.　Nitrogen-doped　SrTiO3　could　be　prepared　by　heating　the　mixture　of　SrTiO3　and　La2O3　under　flowing　NH3　gas　at　600　degrees　C.　The　sample　prepared　with　0.2　mol%　La2O3,　22　mol%　urea　and　77.8　mol%　SrTiO3　which　has　nearly　the　same　nitrogen　and　lanthanum　doping　atomic　fractions　could　be　obtained　by　a　mechanochemical　method　and　exhibited　high　photocatalytic　activities.　Under　the　irradiation　of　light　with　wavelengths　larger　than　400　and　290　nm,　the　photocatalytic　activity　of　nitrogen　and　lanthanum　co-doped　SrTiO3　was　2.6　and　two　times　greater　than　that　of　pure　SrTiO3.　A　new　absorption　edge,　which　was　formed　in　the　visible　light　region　and　higher　visible　light　absorption　after　co-doping　were　the　reason　for　the　high　visible　light　photocatalytic　activity　of　this　substance.　(c)　2004　Elsevier　Ltd.　All　rights　reserved.