A procedure for calculating the adiabat of copper nanopowder is developed. The nanopowder adiabat was determined from numerical calculations at the nano-level performed by the molecular-dynamics method. With the use of this procedure, the problem about copper nanopowder compaction in a metal container under the action of an oblique shock wave was addressed. The temperature rise behind an oblique shock wave in the nanopowder is two orders of magnitude greater than in the micropowder.