Green compacts pressed by means of uniaxial compaction with Magnesia (MgO) powders precipitated from sea water and calcined at different temperatures were sintered tinder H-2 atmosphere at 1700 degrees C. The calcination, carried out between 900 and 1200 degrees C had a great influence in the Final density and the microstruuture. The densification of MgO agglomerated powders seems to be predictably related to grain growth and thus coarsening kinetics, At calcination temperatures higher than 900 degrees C, the volume of large pores was increased notably suggesting that the inhibited grain growth adversely affected the thermodynamics of pore sintering. Relative densities between 74 and 98% of theoretical density were reached in compacts obtained at different compaction pressures. The microstructural differences were examined by Scanning Electron Microscopy (SEM). (c) 2008 Elsevier B.V. All rights reserved.