In this thesis we have studied structural, magnetic , thermal and electrical properties of La 1-x Sr x MnO 3 (x=0.33, 0.55) nanostructures, nanoparticles and thin films. AC susceptibility measurements and memory effect suggest that the nanoparticles of La 1-x Sr x MnO 3 (x=0.33) have superparamagnetic behaviour near room temperature. Also the magneto-traort properties of nanogranular samples are studied. Large low field magnetoresistance and magnetic field sensitivity are observed. A powder sample of this composition shows large conventional magnetocaloric effect above room temperature. Nanoparticles of La 1-x Sr x MnO 3 (x=0.55) show unusual ferromagnetic properties and large inverse magnetocaloric effect. Cooling field and particle size dependence of exchange bias effect have been studied. The coercivity and exchange bias fields decrease exponentially with cooling field. Thin films of La 1-x Sr x MnO 3 (x=0.33) show nonlinear traort properties with large low field magnetoresistance. Keywords: manganite, nanoparticles, thin film, magnetocaloric, exchange bias, superparamagnetism,
