We investigated the electronic and carrier transport properties of Eu-substituted infinite-layered SrFeO2 (Eu:SrFeO2) epitaxial thin films. X-ray photoemission and absorption spectroscopy measurements revealed that the Fe and Eu ions in the Eu:SrFeO2 films were essentially divalent and trivalent, respectively, regardless of the Eu ion content. Based on the transport measurements performed at 300 K, the carrier concentration (n(e)) and Hall mobility of the Eu:SrFeO2 (x=0.15) films were found to be 2.5 x 10(19) cm(-3) and 0.94 cm(2) V-1 s(-1), respectively. The carrier activation efficiency of Eu3+, defined as n(e)/n(Eu) (where n(Eu) is the Eu ion concentration), was as low as similar to 0.9%. We speculate that excess oxygen atoms incorporated between FeO2 sheets behave as carrier compensators and/or strong scatterers. (c) 2013 Elsevier B.V. All rights reserved.