With reference to FIG. 1, a continuous mixer 1 comprises a housing 2 formed with intersecting cylindrical chambers 3 and 4, and a pair of substantially parallel shafts 5 and 6, mounted for rotation within the housing. Paddle members 10 and 11 are mounted on the shafts 5 and 6 so that when the shafts are rotated, each in the same direction, the peripheral parts of the paddle members on one shaft are wiped by the cooperating parts of the paddle members on the other shaft, and vice versa. As shown in FIGS. 4a and 4b, the end faces of each paddle member are formed with lobes, the number of lobes at one end face of the member being different to that at the opposite end face. The arrangement results in continuous distribution, re-orientation and dispersal of material flowing through the mixer.