Method for controlling an internal combustion engine

Process for controlling an internal combustion engine, especially with lean operation, to achieve pre-determined nitrogen oxide emission values comprises controlling the lambda value of a fuel/air mixture to be burnt in the engine or a substitute engine parameter with a clear relationship to the lambda value according to the amount of fuel supplied per unit time or according to the fuel energy supplied per unit time (Q z u). Independent claims are also included for: (1) Control device for carrying out the above process; and (2) Internal combustion engine comprising the above control device. Preferred Features: The fuel is a combustible gas e.g. methane.