Knock‐on electrons produced by muons of different energies have been investigated in lead and copper with a cloud chamber by coincidence and anticoincidence technique. The probability of their production in lead is (5.82 ± 0.71)% per 1.27 cms Pb and in copper (7.64 ± 0.59)% per 1.27 cms Cu. Angles of emergent secondaries in Pb follow a cos2.5 θ distribution and in Cu a cos4 θ distribution. Copyright © 1965 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim