Procedure for obtaining expandable styrene polymers.

Process for preparing expandable styrene polymers (EPS), wherein styrene is polymerized, optionally together with up to 20% of its weight of comonomers, in aqueous suspension in the presence of 0.1 to 25% weight of graphite particles, and at least two organic peroxides a and B which decompose at different temperatures wherein the peroxide a half-life of 1 hour at 80 ° C to 100 ° C, and the peroxide B a period of half-life of 1 hour at 110 ° C to 140 ° C, wherein the peroxide a decomposing at a lower temperature not form or benzoyl radicals benzyl decomposition.