Described herein is a process and an apparatus for polymerizing propylene. The process comprises carrying out the polymerization in at least one slurry reactor and at least one gas phase reactor without recycling unreacted monomers to the slurry reactor. A polymerization product containing unreacted monomers is recovered from the slurry reactor and volatile components are separated from the product in a separation unit. The polymerization product is recovered from the separation unit and conducted to a first gas phase reactor; and at least a part of the volatile components are recovered from the separation unit and conducted them to a gas phase reactor. At least 10 % of the polymer product is produced in the gas phase reactor(s). The invention provides propylene homopolymers and alloys of propylene homopolymers and copolymers having good impact and creep properties.