A process for preparing a silicone sponge roll, which comprises uniformly mixing a foamable silicone composition comprising (A) a vinyl-free organopolysiloxane R.sub.a SiO.sub.(4-a)/2 wherein R is a monovalent hydrocarbon or hydroxyl group and a is 1.95 to 2.05, (B) a finely divided silica filler, (C) an azodicarbonamide foaming agent, and (D) a diacyl peroxide, thereafter extruding the composition through an extruder, and thereafter foaming and vulcanizing the composition. The silicon sponge roll produced is suitable to form a fixing roll for use in electrographic copying machines.