Thermoelectric power studies of cerium substituted Mn-Zn ferrites were investigated from room temperature to well beyond the Curie temperature by the differential method. The Seebeck coefficient is negative for all the compositions showing that these ferrites behave as n-type semiconductors. The values of the charge carrier concentration have been computed from the observed values of the Seebeck coefficient. Plot of Seebeck coefficient (S) versus temperature (T) shows a maximum at Curie temperature (T-c) On the basis of these results an explanation for the conduction mechanism in Mn-Zn-Ce mixed ferrites is suggested. (C) 2003 Published by Elsevier Science B.V.