Rare earth co permeation of K 6HCoGeW 11 O 40 was reported. The co permeation temperature was decided by TG DTA and the ICP results of permeated sample indicate that La and Ce have permeated into the body of this compound. The results of XPS imply that chemical bonds exist between La, Ce and other components of this sample. The XRD patterns show great difference between K 6HCoGeW 11 O 40 and permeated sample. Such result gives evidence that the structure of K 6HCoGeW 11 O 40 is destroyed and new compounds perhaps formed. Four probe method and AC impedance spectra were used to measure the conductivities of K 6HCoGeW 11 O 40 and permeated complex. The conductivity of complex, at room temperature, improves 2.95×10 3 times after being permeated. Analyses of AC impedance spectra of permeated compound at different temperatures show that current carrier has changed. Rare earth co permeation of K 6HCoGeW 11 O 40 was reported. The co permeation temperature was decided by TG DTA and the ICP results of permeated sample indicate that La and Ce have permeated into the body of this compound. The results of XPS imply that chemical The bonds present between La, Ce and other components of this sample. The XRD patterns show great difference between K 6HCoGeW 11 O 40 and permeated sample. Such result gives evidence that the structure of K 6HCoGeW 11 O 40 is destroyed and new compounds may formed. Four probe method and AC impedance spectra were used to measure the conductivities of K 6HCoGeW 11 O 40 and permeated complex. The conductivity of complex, at room temperature, improves 2.95 × 10 3 times after being permeated. Analyzes of AC impedance spectra of permeated compound at different temperatures show that current carrier has changed.