A　series　of　Zn1-xCoxO　nanorods　with　dopant　content　ranging　from　x　=　0.00　to　0.10　was　prepared　by　a　wet　chemical　method.　All　Zn　1-xCoxO　samples　were　investigated　by　x-ray　diffraction,　transmission　electron　microscopy,　energy-dispersion　x-ray　line　mapping　analysis,　and　UV-visible　absorption　spectroscopy.　It　was　found　that　Co2+　ions　were　homogeneously　substituted　for　Zn2+　ions　in　ZnO　nanorods.　Rhodamine　B　degradation　was　used　as　a　probe　reaction　to　evaluate　the　effect　of　Co2+　doping　on　ZnO　nanorods　and　photocatalytic　performance　under　UV　light　and　visible　light　irradiation.　Co2+　ions　acted　as　the　trapping　or　recombination　centers　for　electrons　and　holes,　leading　to　a　reduction　in　photodegradation　efficiency　under　UV　light　illumination.　Alternatively,　Co　2+　ions　enhanced　the　optical　absorption　and　produced　the　photoinduced　carriers　under　visible　illumination　in　terms　of　two　charge　transfer　transitions　involving　Co2+　ions.　Consequently,　Co2+　ions　substituted　in　the　lattice　of　ZnO　nanorods　significantly　improved　the　visible　light　photocatalytic　activity.　©　IOP　Publishing　Ltd.