The silicone rubber obtained by curing in the presence of a platinum-containing catalyst a composition comprising an organopolysiloxane containing a plurality of lower alkenyl radicals and a organohydrogensiloxane consisting essentially of R.sub.3 SiO.sub.1/2 units, R.sub.2 SiO units, RHSiO units, and RSiO.sub.3/2 units in a specified molar ratio is uniquely suitable as the coating material for the press roll in the fixing assembly of an electrophotographic copier.