The fast development of low-temperature geothermal energy affects the search for newer and newer solutions and materials used in the construction of borehole heat exchangers. One of the most important factors affecting the correct operation of heat pump systems with borehole heat exchangers is appropriately selected solidified grout. Solidifies grout has to be characterized by the highest thermal conductivity and good sealing borehole heat exchangers. The paper will present the impact of graphite on the thermal conductivity of solidified grout.