This work deals with the characterization of a power line, devoted to energy distribution and supplied by DC voltage, aiming to use the same line for exchange of information by means of a Power Line Communications (PLC) system. For this purpose, the DC power grid has been considered as a transmission line. The characteristic parameters have been obtained by the short-circuit and open-circuit impedance measurements. Then, the propagation constant and characteristic impedance curve vs. frequency have been calculated. Finally a model of the transmission line has been implemented in Matlab/Simulink® environment and the time domain response of the loaded network has been achieved. Experimental results confirming the validity of the proposed approach and the limitations of the model are given at the end. © 2014 IEEE.