Honeycomb-like structure MgO is prepared from low grade magnesite by a technology including four main steps: calcination of low grade magnesite, carbonization treatment of the calcined magnesite, thermal decomposition of Mg(HCO3)(2) and calcination of basic magnesium carbonate. In this study, the main experimental parameters of carbonization treatment and thermal decomposition were optimized. The carbonization conversion ratio of the calcined magnesite was 93% by controlling the ratio of solid and liquid (calcined ore/water) at 10 g/L, carbonization time at 45 min and CO2 gas flow rate at 0.08 m(3)/h. Decomposition ratio of Mg( HCO3)(2) in solution can reach 88% at 50 degrees C for 60 min via fixing stirring speed at 600 r/min and the Mg2+ content in filtrate at 8 g/L Honeycomb-like structure MgO product with purity of 99% was eventually obtained by calcining basic magnesium carbonate at 800 degrees C for 2 h. The decomposition of basic magnesium carbonate was depicted by TGA. The MgO product was characterized by XRD and SEM. (C) 2013 Elsevier B.V. All rights reserved.