An internal combustion engine 10 has a cylinder head 11 slideably supporting one or more poppet valves 30. At least one of the poppet valves 30 in each combustion chamber of the engine 10 has a primary electrode 69, 269a, 269b, 369a, 369b connected thereto so as to be electrically insulated from the cylinder head 11. The primary electrode 69, 269a, 269b, 369a, 369b forms in combination with one or more secondary electrodes 33, 133, 233, 333, 433, 533 one or more electrode pairs between each of which an electrical discharge is selectively caused to flow so as to initiate combustion in the respective combustion chamber.
