Solid oxide fuel cells using non-glass sealants have become increasingly common. In this paper, fumed silica infiltrated ceramic fiber paper with pre-compression was compared with plain and pre-compressed at 10 MPa hybrid mica as compressive seals. Leakage tests were measured under a 0.1-1.0 MPa compressive load with the pressure gradient varying from 2 to 15 kPa. The results demonstrated that the leakage rate of infiltrated fiber paper was 0.04 scan cm(-1) for a 10 kPa gradient, under 1.0 MPa compressive load, while for mica it was 0.60 and 0.63 sccm cm(-1) which indicated that the infiltrated ceramic fiber paper showed a much lower leakage than mica. Long-term thermal cycling tests demonstrated that although the leakage of fumed silica infiltrated fiber paper was slightly higher than that of hybrid mica, it remained stable after 20 thermal cycles and no interlayer was needed. The mass loss of the fiber paper was 1.7 x 10(-2) mg cm(-2) h(-1) in a hydrogen environment at 1073 K for 200 h. The leakage of infiltrated fiber paper remained about 0.06 sccm cm(-1) after reduction. (C) 2007 Elsevier B.V All rights reserved.