An organoselenium-catalyzed dehydration reaction of anisaldoxime to produce the useful fine chemical anisonitrile was achieved under solventless conditions without using any dehydrant. Simple PhSe(O)OH could be employed as the recyclable and reusable catalyst without obvious deactivation, and the reaction generated no wastes at all. By an easily operable distillation process, the product could be isolated in high purity, as confirmed by NMR spectroscopic analysis. The reaction was scalable to at least kilogram-scale with excellent carbon mass balance at 99.3%, showing very great potential of the method in industrial-scale production. The mechanism of the reaction was also discussed based on the experimental findings.