The electrical resistivity of Fe-Mn alloys with a manganese content of 3.9, 6.0, 8.2, 10.3 and 13.2 at. % Mn was measured in the liquid state by the rotating magnetic field method. The experiments were performed in the heating mode from 1720 to 2070 K and then cooling the sample in an atmosphere of purified helium. For most of the studied alloys, a break in the temperature dependence of the electrical resistance was found when heated to 1900-2000 K. It is established that with the growth of the manganese content in the alloy r and d r/ dT increase. A theoretical calculation of the effective resistivity of the Fe - 10 at. % Mn alloy in the liquid state at temperatures from 1720 to 2770 K is performed. The values of the temperature T *, at which the conductivity of a heterogeneous system becomes equal to the conductivity of an iron solution in manganese with a uniform distribution of atoms, are established. Calculated values of T *= 2050-2100 K are obtained above the temperatures of 1900-2000 K, when heated to which a break in the temperature dependence of the electrical resistance is recorded. The possibility of a percolation transition in heterogeneous Fe-Mn melts is theoretically studied: the limit value of the ratio of the electrical resistivity of the medium and the inclusion at which a percolation transition is possible is established. The flow threshold was defined as the percentage of inclusions at which there is a significant decrease in the effective electrical resistance. The effective electrical resistivity of a heterogeneous melt is calculated using the Maxwell approximation (interpretation by A.A. Snarsky).