Process for hydraulic conveying of polyolefin pellets comprising the steps of: (i) extruding molten polyolefin into strands and cutting the strands into pellets in an underwater pelletiser (A); (ii) withdrawing a first pellet suspension stream (1.1) from the pelletiser; (iii) concentrating the first pellet suspension stream in a first pellet separator (B); (iv) passing the concentrated pellet stream (1.4) to a hydraulic conveying line through a first vessel (D) and mixing it with water thereby producing a second pellet suspension stream (1.5); (v) withdrawing the second pellet suspension stream from the first vessel and passing it to a second pellet separator (E); (vi) separating the pellets from water in the second pellet separator thereby creating a second water stream (1.6) and a dry pellet stream (1.10) and passing the second water stream back to the first vessel; wherein any one of the first or second pellet suspension stream or the dry pellet stream comprises an antiblock.