The X-ray diffraction has revealed that CuIn5S8 is a single phase crystal of cubic spinet structure. The value of the unit cell parameter for this crystal is 1.06736 nm. The crystal is assigned to the conventional space group Fd3m. The photocurrent is found to have the characteristic of monomolecular and bimolecular recombination at low and high illumination intensities, respectively. The electrical resistivity and Hall effect of CuIn5S8 crystals are measured in the temperature range of 50-400 K. The crystals are found to be intrinsic and extrinsic above and below 300 K, respectively. An energy band gap of similar to1.35 eV at 0 K, a carrier effective mass of 0.2 m(0), an acceptor to donor concentration ratio of 0.9, an acoustic phonon deformation potential of 10 eV and a nonpolar optical phonon deformation potential of 15 eV are identified from the resistivity and Hall measurements. The Hall mobility data are analyzed assuming the carrier scattering by polar optical phonons, acoustic combined with nonpolar optical phonons, and ionized impurities.