Thin films of CuInSe2 have been prepared by selenizing co-sputtered Cu-In films with selenium vapor. X-ray diffraction, Auger electron spectroscopy, electrical conductivity and optical transmission measurements were used to characterize the specimens. In very Cu-rich films, Cu-Se segregations were identified and a strong (112) orientation was observed. No preferential crystallite orientation was detected in near-stoichiometric and In-rich films. The conductivity types were p-type for Cu-rich and n-type for near-stoichiometric and In-rich films. Conductivity measurements were performed on several n-type films in the temperature range 77-370 K. All samples showed a thermally activated conductivity for higher temperatures and the variable-range hopping conduction mechanism in the lower temperature range. The dependence of the absorption coefficient on incident photon energy indicates allowed direct transitions with energies in the range 0.96-1.01 eV.