Thermal decomposition of the citrate-gel precursors with La/Ni = 1/1 and La/Ni = 3/2 results in the formation at T ≥ 700 °C the single phase perovskite LaNiO3 and the disordered perovskite-like phase La3Ni2O6+x. A reduction of both compounds during thermal processing in a 5 % H2/Ar gas mixture proceeds in two definite steps. The first stage of LaNiO3 reduction at 250 - 350 °C results in the formation of an O-deficient La2Ni2O5 compound. A similar process during the reduction of La3Ni2O6+x occurs at 300–400 °C with the lack of significant changes in the XRD pattern. An unusual feature of these processes deals with the formation of Ni0 nanoparticles on the surface of both reduction intermediates at 350–400 °C while similar processes are usually observed during redox exsolution of metals from several complex oxides at T > 700 °C only. As-obtained Ni/LaxNiOy nanocomposites demonstrated significant catalytic activity and excellent selectivity and stability in the Sabatier reaction.