A method of cleaning a gas inlet nozzle of an abatement burner combustion chamber. The abatement burner intermittently receives gas for combustion from a feed process. The nozzle comprises a cleaning mechanism including a movable cleaning member for physically removing unwanted deposits from the nozzle. The cleaning member is movable from a retracted first position wherein the cleaning member is outside a path of a flame associated with the nozzle, to a second cleaning position wherein the cleaning member is in a path of the flame associated with the nozzle. The method comprises the steps of: a. identifying when the nozzle is out of use; b. moving the cleaning member from the first position to the second position while the nozzle is out of use; and c. returning the cleaning member to the first position before nozzle is in use.