Résumé : The top-quark pair production cross section is measured in final states with one electron or muon and one hadronically decaying τ lepton from the process tt→(ℓνℓ)(τντ)bb-, where ℓ=e,μ. The data sample corresponds to an integrated luminosity of 19.6 fb-1 collected with the CMS detector in proton-proton collisions at √s=8 TeV. The measured cross section σtt-=257±3 (stat)±24 (syst)±7 (lumi) pb, assuming a top-quark mass of 172.5 GeV, is consistent with the standard model prediction.