La/Mg ratio was evaluated in Ni–Mg–La–Al catalysts for the biogas dry reforming. The reactions were carried out in a fixed bed tubular reactor using synthetic biogas (70% CH₄ and 30% CO₂). The catalyst characterization showed that the increase of La/Mg ratio decreased the specific surface area of the catalyst and the average crystallite size of Ni⁰, but increased the acid strength of sites identified by NH₃-TPD analysis. These properties contributed to improving the activity and catalytic stability for CH₄ conversion at 700 °C. The Mg presence increased the strength of basic sites of the catalysts and plays an important role in CO₂ conversion. The catalyst with La/Mg = 4 presented the best activity and stability for the reaction at 700 °C, due to the greater resistance to sintering associated with de small size of Ni⁰, and a proper combination of acid and basic sites. H₂/CO ratios higher than 1 were obtained due to the contribution of the CH₄ decomposition reaction.