Gel formation was realized by adding citric acid to a solution of La(NO3)(3)center dot 5H(2)O, Ca(NO3)(2)center dot 4H(2)O, and Fe(NO3)(2)center dot 9H(2)O. Perovskite-type (La1-xCax)FeO3 (0 <= x <= 0.2) was synthesized by firing the gel at 500 degrees C in air for 1 h. The crystallite size (D-1 2 1) decreased with increasing x, while the specific surface area was 6.8-9.4 m(2)/g and independent of x. The XPS measurement of the (La1-xCax)FeO3 surface indicated that the Ca2+ ion content increased with increasing x, while the Fe ion content was independent of x. Catalytic activity for CO oxidation increased with increasing x. (c) 2005 Elsevier Ltd. All rights reserved.