Agro-energy crop, Miscanthus × giganteus should be produced on marginal land in order to avoid land suitable for food production. Production of electricity in thermal power plants occupies large land areas by depositing tailings from surface mines, and depositing ash and slag. During the first year of Miscanthus × giganteus growing in containers, the concentration of heavy metals: As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and Fe was monitored in underground and aboveground plant parts. The substrate was overburden from open pit coal mine RB Kolubara and ash from TPP Nikola Tesla B. Significant differences were found between the substrate and the investigated elements, but in all cases the accumulated heavy metals almost completely remained stable in underground organs of plant. It can be concluded that biomass of Miscanthus × giganteus could be used as energy source if it is grown on a soil moderately contaminated by heavy metals.