An improved process for molding and vulcanizing rubber products using a curing bladder, characterized in that the bladder is one which is made of a rubber compound containing (A) organic rubber and (B) polyorganosiloxane, the ratio of (A)/(B) being 95/5 to 5/95, or the bladder is one which is produced by surface treating (A) organic rubber with a silicone composition containing (A) organic rubber and (B) polyorganosiloxane, said polyorganosiloxane comprising at least two monovalent substituted or unsubstituted hydrocarbon groups having five or more carbon atoms and a C.dbd.C double bond connected to the silicon atom through at least one carbon atom, and having a degree of polymerization greater than 20.