This invention relates to a process to produce propylene polymers comprising contacting a metallocene catalyst compound and an activator in a reaction medium comprising propylene, from 0 to 30 volume % of one or more solvents and from 0 to 30 mole % of one or more comonomers, under temperature and pressure conditions below the melting point of the propylene polymer and where: a) the temperature is at or above the critical temperature for the reaction medium, and the pressure is at least 500 kPa above the critical pressure of the reaction medium; or b) the temperature is 1.degree. C. or more above the critical temperature for the reaction medium, and the pressure is at or above the critical pressure of the reaction medium; or c) the temperature is 1.degree. C. or more above the critical temperature for the reaction medium, and the pressure is at least 500 kPa above the critical pressure of the reaction medium.