Ferrites of the composition Co0.7+x Zn0.3 Six Fe2-2x O4 (x = 0.0, 0.1, 0.15, 0.2, 0.25, 3, 4) are prepared by double sintering ceramic method. X-ray diffraction patterns of all the samples show cubic spinal phase. By comparing the calculated and observed X-ray intensity ratios I220/I400 and I400/ I422 and using site preference of various ions, the cation distribution of the present system is determined. At lower concentration of Si up to x = 0.15, the dc resistively (__ampersandsignrho;dc) increases and for x __ampersandsigngt; 0.15, __ampersandsignrho;dc is found to decrease. With increase in temperature, dc resistively decreases except for higher concentration of Si (x = 0.3 and 0.4) which show increase in resistivity at lower temperature. Activation energy values show one to one correspondence with resistivity values. Curie temperature is found to decrease with increase in Si concentration.