A system to supply hydrogen-rich fuel to an internal combustion engine, whereby a hydrogen-rich gas is produced from a liquid raw fuel by a hydrogen generator. The exhaust line of the internal combustion engine contains an exhaust purification system, such as a DeNOx catalytic converter, which is at least temporarily supplied with hydrogen-rich gas through a bypass line. In addition, the exhaust line is in thermal contact with the hydrogen generator in order to recover thermal energy.