In this work, nanomaterials based on FeIIICoII and FeIIINiII mixed oxides were obtained for the first time by thermal decomposition of polymer complexes of Fe and Co or Ni nitrates with acrylamide. During thermolysis, core‐shell nanomaterials are formed containing nanoparticles of FeCo and FeNi oxides uniformly distributed inside the carbon layer. These nanomaterials are characterized by high chemical and thermal stability. During thermolysis, nanoparticles of mixed oxides FeCo and FeNi were formed with an average crystallite size of 13–22 and 22–33 nm, respectively. Nanomaterials were tested as antifriction and antiwear additives to liquid industrial oil I‐20 A. The values of the friction coefficient decrease by more than 60 % when CoO⋅Fe2O3 with a concentration of 0.05 % is added to the industrial oil I‐20 A.