Oxidation resistance of sintered ${eta}-FeSi_{2}$ was investigated at intermediate temperature range in air atmosphere. Fully dense and porous bodies of ${eta}-FeSi_{2}$ samples were fabricated by using the Spark Plasma Sintering (SPS). They were annealed at $900^{circ}C$ for 5days to obtain ${eta}-FeSi_{2}$ phase. The bulk samples were oxidized at $800,;900;and;950^{circ}C$ in air atmosphere. The high temperature oxidation tests reveal that amorphous $SiO_{2}$ layer, similar to Si was formed and grew parabolically on ${eta}-FeSi_{2}$. Accelerated oxidation is not observed as well as cracks and grain boundary oxidation. Granular ${varepsilon}-FeSi$ was developed below the oxide layer as a result of oxidation of ${eta}-FeSi_{2}$. Oxidation resistance of sintered ${eta}-FeSi_{2}$ was excellent for high-temperature thermoelectric application.