Dataset for article "Nanostructured La0.75Sr0.25Cr0.5Mn0.5O3–Ce0.8Sm0.2O2 Heterointerfaces as All-Ceramic Functional Layers for Solid Oxide Fuel Cell Applications" published in ACS Appl. Mater. Interfaces 2022. The data includes: Schematic on the nanostructures fabricated for the work (Figure 1) Top view AFM images of the nanostructures studied (Figure 3) TEM-EDX images of the nanostructures studied (Figure 4) ASTAR analysis of the nanostructures studied (Figure 5) X-Ray Diffraction data of thin films with composition: La0.75Sr0.25Cr0.5Mn0.5O3 (LSCrMn), Ce0.8Sm0.2O2 (SDC), and two La0.75Sr0.25Cr0.5Mn0.5O3–Ce0.8Sm0.2O2 (LSCrMn-SDC) nanostructures -bilayer (BL) and nanocomposite (NC)- Electrochemical Impedance Spectroscopy raw data for LSCrMn, SDC and LSCrMn-SDC thin films measured under air and wet hydrogen atmospheres at different temperatures (630-750 ºC) Arrhenius analysis of the area specific resistance (ASR) of the films under air and hydrogen atmospheres In-plane conductivity evolution with temperature data measured under air and 5% hydrogen atmospheres of the two LSCrMn-SDC nanostructures ASR evolution with time measured for over 400 h at 780 ºC