X-ray powder diffraction data were obtained for Cu3In5Se9 and Cu3In5Te9 which were found to crystallize in orthorhombic and tetragonal systems, respectively. The electrical resistivities and Hall mobilities of these compounds were investigated in the temperature range 35-475 K. Cu3In5Se9 was identified to be n-type with a room temperature resistivity of 3 x 10(3) Omega.cm which decreases with increasing temperature. For T < 65 K impurity activation energy of 0.03 eV and for T > 350 K onset of intrinsic conduction yielding a band gap energy of 0.99 eV were detected. The neutral impurity scattering was found to dominate at low temperatures, while in the high temperature region thermally activated mobility was observed. Cu3In5Te9 exhibits p-type conduction with a room temperature resistivity of 8.5 x 10(-3) Omega.cm decreasing sharply above 400 K and yielding an impurity ionization energy of 0.13 eV. The temperature dependence of mobility indicates the presence of lattice and ionized impurity scattering mechanisms above and below 160 K, respectively.