Method for operating a spark-ignited internalcombustion engine

A method for operating a spark-ignited internal combustion engine with at least one piston movable in at least one cylinder and at least one prechamber connected to the at least one cylinder, the method comprising the steps of: - forming a combustible mixture by mixing a first fuel and air in a largely homogeneous manner and supplying this mixture to the at least one cylinder in an intake stroke, - compressing the combustible mixture with the piston in a compression stroke, thereby supplying a portion of the combustible mixture to the prechamber, - supplying a second fuel to the prechamber during the intake and/or the compression stroke at a supply time before the start of combustion, wherein the second fuel has the same or a different chemical composition and/or concentration with respect to the first fuel, - spark ignition in the prechamber characterized in that an amount of second fuel and/or the chemical composition of the second fuel which is introduced into the prechamber and/or the ignition timing of the prechamber and/or a temperature of the cylinder charge are selected such that a desired combustion duration can be achieved.