The effects of modifiers and process conditions on synthesis of magnesium oxide by the carbonatization method and properties of the product are studied. Magnesium carbonate obtained from magnesium hydroxide and carbon dioxide was subjected to thermal decomposition at 800oC. The reaction of precipitation was performed checking the influence of temperature, rate and mode of reagents introduction, type and concentration of the modifier. The modifiers were the non-ionic compounds from the group of poly(ethylene glycols). The magnesium oxides produced were characterised by determination of their dispersive- morphological properties, wettability profiles, specific surface area, total volume and mean size of pores. The products were also subjected to identification by the X-ray diffraction method and TG/DTA analysis. The results revealed a significant impact of the concentration and type of modifiers on the physicochemical properties of MgO samples obtained and permitted selection of the best products for particular applications.