This paper introduces a plasma reactor for short-time plasma surface modification of polymer powders. This reactor type, the so-called plasma downer reactor (PDR), provides a high reaction rate, which is forced by the high gas velocity and high particle dispersion in the plasma. It combines the advantageous characteristics of the downer principle for the fluid dynamics of gas-solid phases with plasma surface modification. This work demonstrates that a very short plasma exposure time of 0.1 s effectively improves the wettability of HDPE and Co-PA powders. The water contact angles of HDPE and Co-PA powder can be reduced to 72degrees and 76degrees, respectively. The surface tensions of both polymer powders could be increased by a factor of 2 up to 43 mN/m. Water/polymer suspensions and pastes can be made without tensides.