The perovskite-like La2-xSrxCoO4 +/- lambda. (x = 0.0-1.0) mixed oxides of K2NiF4 structure were prepared by the polyglycol gel method and used successfully for CO and C3H8 oxidation; these samples were investigated by using the XRD, IR, TEM, BET, TPD and iodometry methods; and the effects of coefficient x on their structure and catalytic activities of these samples were studied for the first time. The results show that La2CoO4 has orthorhombic K2NiF4-type structure, when La3+ is substituted by Sr2+, whose ionic radius (r(Sr)(2+) = 0.1310 nm) is larger than that of La3+ (r(La)(3+) = 0.1216 nm), the structure factor increases, and this leads to the structure change from orthorhombic (O) system to tetragonal (T) system; in addition, these catalysts possess different catalytic activities towards the oxidation of CO and C3H8, and the catalytic activity of LaSrCoO4 is better than that of other samples in oxidation reaction, this is explained in terms of their structure: mobile lattice oxygen, content of Co3+, particle sizes and BET surface areas. (C) 2004 Elsevier B.V. All rights reserved.