A silicone rubber composition suitable for hot-air vulcanization under normal pressure without the disadvantages of surface tackiness and internal voids in the cured rubber products and also free from the problems of corrosiveness to metals and toxicity to workers, which comprises, as the curing agent for the organopolysiloxane, a peroxide derivative of dibenzoyl peroxide which is substituted on each of the benzene nuclei with substituted silyl, e.g. trimethyl silyl, group or a silyl-substituted methyl, e.g. trimethylsilyl methyl, group.