Spark plug

A spark plug 100 comprises a housing 2 and an insulator 4 for electrically insulating a centre electrode 6 provided at least partly on the inside of the insulator. The housing of the spark plug is configured such that in a mounted state, an annular gap 8 is formed between the housing and the insulator. The annular gap is filled with a heat conducting element 10. The heat-conducting element may be configured such that it extends to a lowermost point of the annular gap, preferably extending from the lowermost point of the annular gap to a filling height H corresponding to a stepped portion 6A of the centre electrode. The heat-conducting element may comprise a liquid such as a heat-conducting paste, a liquid metal, or an oil, e.g. silicon oil, lubricating oil and/or engine oil. The heat-conducting element may comprise a solid structure, a granular material, a solder or a powder, e.g. metal, ceramic and/or polymer particles.