The nanocomposites of highly-dispersed MnO_x and CeO_x on carbon nanotubes (CNTs) with a uniform structure are obtained via a novel in situ deposition strategy through a pyridine-thermal method and used for selective catalytic reduction (SCR) of NO with NH₃ at low temperature. The influence of calcination temperature and the promotion effect of CeO_x on the structural features of the MnO_x–CeO_x/CNTs are investigated. It is found that the appropriate calcination temperature could provide perfect crystallization and good dispersion of MnO_x and CeO_x components. The suitable CeO_x loadings in the MnO_x–CeO_x/CNTs will lead to enhanced reducing ability, suggesting stronger interaction between CeO_x, MnO_x and CNTs. Compared with the MnO_x–CeO_x/CNTs prepared by an impregnation method, the MnO_x–CeO_x/CNTs obtained from the pyridine-thermal route presents better NH₃-SCR activity within the working temperature range, excellent SO₂ resistance as well as favourable stability. The MnO_x–CeO_x/CNT nanocomposites prepared by the pyridine-thermal route are good candidate catalysts for the NH₃-SCR of NO.