A method of improving the starting characteristics of spark plugs involving the use of polonium is described. Results of experiments concerned with the measurement of the apparent breakdown voltage under laboratory conditions and the starting characteristics of spark plugs in internal combustion motors at low temperatures are given. These results indicate that the use of polonium in commercially practical concentrations in standard electrode alloys definitely improves the starting performance of spark plugs. Large scale methods of extraction of polonium from residues of a radium refinery and the method of introducing polonium into the electrode alloy are to be discussed in a subsequent article.