The thermal stability of Ni,Al-CO3 hydrotalcite-like compounds synthesized by the coprecipitation method and aged upon microwave-hydrothermal treatment for different periods of time was studied. The samples prepared were characterized by Elemental Analysis, PXRD, Thermal analyses (DTA and TG) and Temperature Programmed Reduction (TPR). The results show that the use of microwave radiation as a source of heating during the ageing treatment leads to an increase in the crystallinity of the solids, which determines their thermal stability.