A direct oxidative C-H cyanation of quinoline and its derivatives using trimethylsilyl cyanide as the cyano source and molecular oxygen as the terminal oxidant has been developed. In the presence of catalytic amounts of vanadium-containing heteropoly acids, e.g., H7PV4Mo8O40, cyanation of various quinoline and its derivatives preferentially took place at the 4-position, affording the corresponding substituted 4-cyanoquinolines as the major products.