Y-type hexagonal ferrites were prepared by citrate sol-gel auto-combustion method (CSAM). The phase formation process, microstructure and magnetic properties were investigated and compared with those of the samples made by conventional solid-state reaction method (SSRM). The selected material system has stoichiometric composition of Ba2Zn1.2-xCoxCu0.18Fe12O22, where x was varied from 0 to 1.2. Phase formation was characterized by powder X-ray diffraction (XRD). The microstructure was observed via scanning electron microscopy (SEM). Frequency spectra of complex permeability were measured via an impedance analyzer. Results reveal auto-combusted powders are about 22 nm and very active. Phase formation temperature and sintering temperature are both 900 degrees C, much lower than those in SSRM. The sintered samples have fine-grained microstructure. The samples exhibit better magnetic properties in hyper-frequency than those made by SSRM. As zinc content increases, the permeability mu' is enhanced and the cut-off frequency drops. The magnetic properties are also correlated with the sintering temperature and microstructure. Permeability mu' increases with the rise of sintering temperature. (c) 2005 Elsevier B.V. All rights reserved.