Gd-doped ceria (GDC, Ce0.86Gd0.14O2−δ) films are deposited on conductive substrates by RF-magnetron sputtering and their across-plane electrical conductivities (perpendicular to film plane) are measured as a function of temperature (300≤T≤400°C) and oxygen partial pressure (Po2) to assess the feasibility of their use as an electrolyte in miniaturized solid oxide fuel cells (micro-SOFCs). The films deposited at relatively high T=500°C, deposited on either dense or porous substrate, show columnar grains with diameter 200nm. The magnitude of conductivities in air is similar to those of pellet-form GDC. However, the electronic conductivities of GDC films in low Po2 are higher than that of pellet. •GDC films were deposited by RF-sputter on dense or porous conductive substrate.•Ionic and electronic conductivities were measured in across-plane mode.•Grain and grain boundary resistances were not distinguishable in impedance spectra.•Ionic conductivities of films were slightly higher than that of the pellet.•Electronic conductivity was increased due possibly to small grains or columns.