Abstract: A high-pressure pump includes a housing accommodating a movable piston. The piston defines a chamber which is divided by means of a partition member into two spaces substantially insulated from each other. One space communicates with a working medium source and with a consumer via non-return valves. The other space communicates, on one side, with a source of sealing medium via a non-return valve, and on the other side, with the same source, via a slit seal formed between the pump housing and the piston. The partition member is movable and is mounted coaxially with the piston. In order to limit the displacement of the partition member during the intake stroke within the housing, there is provided a stop mounted within the space communicating with the working medium source and rigidly connected with the pump housing.