In this work, we present a synthetic protocol for production of sub 10 nm copper nanopowder (CuNPs) using continuous stirred tank (CSTR) and tubular flow reactors (PFR). Substantially higher throughputs of CuNPs have been achieved in this new protocol by reducing a copper salt with hydrazine hydrate/sodium borohydride as reducing agent. Copper nanopowder can be prepared from the sol by high speed centrifugation of the colloid. The nanopowder preserves size and shape upon re-dispersion. It has been shown that the contacting patterns do not have significant effect on particle size and shape but the overall yield is heavily dependent on the contacting pattern and reactor design. Scaling has been identified as a key issue in determining the yield. © 2016 Elsevier B.V.