Method and apparatus for the operation of a gas reformer in conjunction with an internal-combustion engine for the purpose of reducing the pollution of the exhaust gases in which a mixture of fuel and primary air and/or exhaust gas is converted into sootfree reformed gas in the gas reformer in the presence of a catalyst; the reformed gas and secondary air are then supplied to the internal-combustion engine may be recirculated through the gas reformer. From start-up to warm-up to operation under load, fuel is mixed with a decreasing percentage of slightly understochiometric supply of primary air. For operation under load, the primary air is largely replaced by exhaust gas which heats up the mixture fed to the catalyst in the gas reformer. During operation under load, reformed gas is generated as needed by the internal-combustion engine by supplying fuel, exhaust gas and primary air in accordance with the temperature of the catalyst.