La1-xSrxMnO3 (x = 0.3) (LSM) nanoparticles were prepared by a sonication-assisted coprecipitation method. The coprecipitation reaction is carried out with ultrasound radiation. Lower sintering temperatures are required for the sonication-assisted product. Fully crystallized LSM with an average particle size 24 nm is obtained after the as-prepared mixture is annealed at 900 degreesC for 2 h. Magnetic properties indicate that the transition temperature from the paramagnetic to ferromagnetic state of the sample is quite sharp and occurs at 366 K for samples annealed for 2 h at 900 and 1100 degreesC. (C) 2002 Elsevier Science Ltd. All rights reserved.