Mesoporous MgAl2O4+ LnFe0.7Ni0.3O3 (Ln=La, Pr) nanocomposites were prepared by inexpensive one-pot procedure with Pluronic P123 copolymer, Ni+Ru active component was supported by wet impregnation. The real structure of samples was studied by XRD and TEM with EDX, surface properties by FTIRS of adsorbed CO, reactivity by H2 –TPR, catalytic activity was tested in ethanol steam reforming. Disordering of the real structure of nanocomposite supports due to incorporation of transition metal cations into MgAl2O4 results in developed metal-support interface and domination of single surface metal centers. This provides a high catalytic activity in reaction of ethanol steam reforming in the intermediate temperature range ~550 oC close to that of the best known catalysts, and stability to coking. A higher activity for Pr-containing catalyst is provided by a high reactivity of surface oxygen species bound with Pr cations.