Exhaust purification system of an internal combustion engine

An exhaust purification system of an internal combustion engine comprising:

• a reformer,
• an exhaust treatment catalyst arranged in an engine exhaust passage,
• a hydrogen supply pipe inserted inside the engine exhaust passage upstream of the exhaust treatment catalyst, hydrogen generated in the reformer being supplied to the engine exhaust passage upstream of the exhaust treatment catalyst via the hydrogen supply pipe, and
• heat exchange fins formed on an outer circumferential surface of the hydrogen supply pipe for heat exchange with exhaust gas flowing through an inside of the engine exhaust passage.