Perovskite-type thin films of lanthanum manganese oxide (LaMnO3) were prepared on yttria (8%) stabilized zirconia substrate by the sol-gel process from an alkoxide solution of lanthanum isopropoxide (La(O-i-C3H7)(3)) and manganese isopropoxide (Mn(O-i-C3H7)(2)). The alkoxide solution was chelated with 2-ethyacetoacetate, and further modified with polyethylene glycol (PEG). The obtained LaMnO3 thin film was transparent and macroscopically crackless. X-ray diffraction, differential thermal analysis-thermogravimetry analysis, and scanning electron microscope observations indicated that single-phase LaMnO3 thin films with a grain size of 80 to 100 mn are formed when a spin-coated LaMnO3 gelled film is heated at 600 degreesC for I h. The porous and homogeneous grain structure with a grain size of < 100 nm can be obtained when the LaMnO3 gelled film is heated at 600 degrees and 800 degreesC. It was considered that PEG might accelerate the crystallization of the perovskite phase, which indicates that PEG assists the formation of the La-O-Mn frame network during partial hydrolysis and condensation reactions in sol-gel processes.