A measuring system for determining the specific electrical conductivity of a medium in a vessel, comprising an inductive conductivity sensor with at least one transmitter coil that emits an input signal into the medium and a receiver coil connected to the transmitter coil via the medium that delivers the output signal, a temperature sensor for measuring the temperature of the medium, and a data processing unit that determines the conductivity of the medium using the input signal, the output signal, and the temperature provided. The system is characterized by the fact that the conductivity sensor and the temperature sensor are designed as non-invasive sensors.