Résumé : Measurements of prompt ψ(2S) meson production cross sections in proton–lead (pPb) and proton–proton (pp) collisions at a nucleon–nucleon center-of-mass energy of s NN =5.02TeV are reported. The results are based on pPb and pp data collected by the CMS experiment at the LHC, corresponding to integrated luminosities of 34.6 nb −1 and 28.0 pb −1 , respectively. The nuclear modification factor R pPb is measured for prompt ψ(2S) in the transverse momentum range 4