The Ni/SiO2 catalyst was modified by BaO in order to improve the thermal stability and the carbon deposition resistance during the combination of CO, reforming and partial oxidation of methane using a fluidized bed reactor, it is possible to convert methane into syngas with low H-2/CO ratio (1 < H-2/CO < 2) at above 85% methane conversion without catalyst deactivation in 10 h, in a most energy efficient and safe manner, requiring little or no external energy. Samples of the catalysts were characterized using TPR, X-ray diffraction (XRD) and TEM techniques, indicate that Ni agglomerating is a major reason for deactivation, addition of BaO might be responsible for its high activity and resistance to sintering because it can produce a highly dispersed active surface area as bound-state Ni species when the catalyst is prepared at high calcined temperatures. The addition of BaO as silica gel modifiers can be beneficial for the performance of the Ni/SiO2 catalyst. (C) 2003 Elsevier B.V. All rights reserved.