A dispenser (1) for filling a receptacle (R) with viscous material (30), said dispenser (1) comprising, a cylinder (2, 22), a main piston (4), a driving device, an auxiliary piston (5) and a space (S). The cylinder (2, 22) is arranged to be connected to a container (3) for the viscous material (30), and the main piston (4) is axially movable in the cylinder (2, 22) and arranged for both sucking and discharge the viscous material (30) from the cylinder (2, 22) through the outlet port (23). The driving device is arranged for moving the main piston (4). The main piston (4) and the auxiliary piston (5) are axially movable in the cylinder (2, 22). The space (S) being formed between the pistons (4, 5) and constituting a dosing chamber arranged for receiving viscous material (30) from the inlet port (21) and the pistons (4, 5) are further arranged to discharge viscous material (30) from the dosing chamber (S) through the outlet port (23).
