This paper describes the obtention of LaCoO3 nanopowders by the co-precipitate method with ammonium hydroxide from solvent such as water, ethyl alcohol and ethylene glycol. The crystalline structure and average particle size are dependent of type-solvent. The XRD patterns indicated that the LaCoO3 nanopowders prepared with water and ethyl alcohol exhibit a pure perovskite-type LaCoO3 in the rhombohedra structure. The average diameter of the particles prepared with ethyl alcohol and water are 27 +/- 4.49 nm and 64.4 +/- 12.92 nm respectively. High resolution transmission electron microcopy revealed an oriented attachment mechanism for the growth of aggregated LaCoO3 nanocrystals. Room temperature magnetization results of the heat treated LaCoO3 nanopowders exhibited a paramagnetic behavior. The average particle size and formation temperature of LaCoO3 obtained in this study is comparatively lower than those reported in the literature. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.