The Ni-Co/Al2O3-MgO nanocatalysts with different Al/Mg ratios were synthesized via sonochemistry method and applied in CH4/CO2 reforming. In order to investigate the effect of ultrasonic irradiation, Ni-Co/Al2O3-MgO nanocatalyst with Al2O3/MgO = 1.5 was also prepared via impregnation method. All samples were characterized by XRD, FESEM, PSD, BET and FTIR techniques. However, it should be noted that the sonochemistry method results in a better dispersion, smaller particle size, higher specific area and uniform morphology as well as better catalytic performance in comparison with the impregnation. Although among the prepared samples via sonochemistry, the Ni-Co/Al2O3-MgO nanocatalyst with Al2O3/MgO = 5 showed higher dispersion, better morphology, smaller crystal size, superior active phase distribution and higher specific surface area. Due to the better textural properties, the Ni-Co/Al2O3-MgO nanocatalyst with Al2O3/MgO = 5 shows a good catalytic performance, consequently. (C) 2015 Elsevier Ltd. All rights reserved.