Mesostructured vanadium-magnesium oxides (V-Mg-O) were synthesized using vanadium pentoxide and magnesium nitrate as sources and cetyltrimethylammonium bromide (CTAB) or the mixture of CTAB and hexadecylamine (HDA) as template. The effects of surfactant concentration, pH of the reaction medium, aging time, and temperature as well as aging mode (static or dynamic) were systematically investigated. The pH of the reaction medium and the surfactant concentration and nature were found to be the key parameters in the formation of V-Mg-O mesophases. When CTAB was employed alone as template and its concentration was higher than the critical micelle concentration, single lamellar mesophases were obtained in both acidic and neutral media. When the mixture of surfactants was used as template and its concentration was sufficiently low, only microporous phases were obtained in strongly acidic media (pH less than or equal to 4), even at elevated aging temperatures and/or for long aging times. A mixture of mesophases could be, however, obtained in weakly acidic and neutral media (pH = 4-7). At high surfactant concentrations, a single lamellar structure was generated in strongly acidic media and a mixture of mesophases in the weakly acidic and neutral ones. Only amorphous solids were generated in the basic range of pH, regardless of the surfactant concentration employed. With the change in aging time, numerous metastable phases have been identified, particularly in weakly acidic and neutral media. Some comments about the mechanisms of formation of the mesophases conclude the paper.