Abstract. The exclusive deep inelastic electroproduction of ψ(2S ) and J/ψ(1S ) at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2 < Q 2 < 80 GeV 2 , 30 < W < 210 GeV and |t| < 1 GeV 2 , where Q 2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The data for 2 < Q 2 < 5 GeV 2 were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb −1 . The data for 5 < Q 2 < 80 GeV 2 are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb −1 . The decay modes analysed were μ + μ − and J/ψ(1S ) π + π − for the ψ(2S ) and μ + μ − for the J/ψ(1S ). The cross-section ratio σ ψ(2S ) /σ J/ψ(1S ) has been measured as a function of Q 2 , W and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.Exclusive electroproduction of vector mesons in deep inelastic scattering at high energies, ep → eV p, where V denotes a vector meson, may be described as a multi-step process. The electron emits a virtual photon, γ * , with virtuality Q 2 and γ * p centre-of-mass energy W, the virtual photon fluctuates into a qq pair and which subsequently interacts with the proton via a colour-neutral exchange, e.g. through a two-gluon ladder, and then hadronises into the vector meson. The ψ(2S ) and the J/ψ(1S ) have the same quark content, different radial distributions of the wave functions, and their mass difference is small compared to the HERA centre-of-mass energy. Therefore, the ratio of their electroproduction cross sections allows checking perturbative QCD predictions regarding their wave functions [1].The luminosity used for this analysis was 468 pb −1 in total, which consists of data from 1996-2000 and 2002-2007 running periods (HERA I and HERA II, respectively). The kinematic range was 2 < Q 2 < 80 GeV 2 , 30 < W < 210 GeV and |t| < 1 GeV 2 . Events were selected with no activity in the central ZEUS detector in addition to signals from the scattered electron and the decay products of the studied mesons. The sample contained exclusive and a small fraction of proton-dissociative events with diffractive masses M Y < 4 GeV which was assumed to cancel in the cross section ratio. The decay channels were: J/ψ(1S ), ψ(2S ) → μ + μ − , and ψ(2S ) → J/ψ(1S )π + π − with the subsequent decay J/ψ(1S ) → μ + μ − . The analysis was based on data collected with the ZEUS detector when 920(820) GeV protons collided with 27.5 GeV electrons or positrons. The DIFFVM [2] Monte Carlo (MC) was used for simulating the studied process. Exclusive and diffractive Bethe-Heitler dimuon production were simulated using the GRAPE package [3]. The results for the three cross-section