Résumé : A sample of 357 events fitting the reaction ν + p → μ- + p + π+ on free proton is obtained from the Gargamelle neutrino propane experiment at the CERN-PS. The average value of the cross section above 1 GeV is found to be (0.60 ± 0.07) 10-38 cm2. The reaction is dominated by the production of the Δ++(1232) resonance. Results on the Δ++ spin density matrix are given. © 1978.