Abstract: A spark ignition circuit comprising a first capacitor arranged to be charged from a mains power supply through rectifying means and discharged through the primary of a transformer to produce sparking across a spark gap in the secondary circuit of the transformer in response to the operation of a triggerable switching means under the control of a timing circuit connected across the first capacitor and including a second capacitor, the charge voltage of which when it exceeds a predetermined level causes an arc discharge device to break down and the triggerable switching means to be triggered. When the triggerable switching device conducts, the first capacitor will be discharged. The circuit will continue to produce sparks at a rate determined by the timing circuit until such time as gas in the vicinity of a spark gap is ignited. Flame sensing and re-ignition facilities may also be provided. Examples of suitable arc-discharge devices are also disclosed.