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Ni-based Fe-Ni-Cr alloy is an important engineering material for a variety of applications especially at high temperature conditions. However, during service, this alloy experienced an oxide exfoliation that may reduce the material lifetime and its potential applications. To enhance the protective properties of this alloy at high temperature application, the modification on the alloy surface was done to introduce the subsurface region of refined grain that will induce diffusion. This project is to study the effect of different surface preparation on the isothermal oxidation behavior of Fe-Ni-Cr alloy. Different grit of SiC papers were used during grinding processes, namely P180, P600 and P1000 in order to achieve different surface roughness of the samples. The ground samples were exposed to oxidizing temperature at 700°C in air for 150 hours. The isothermally oxidized alloys were analyzed using kinetics of oxidation and scanning electron microscope equipped with energy dispersive x-ray spectrometer. Oxides layers were formed on the alloy surface which act as a protective layer at the isothermal temperature condition. As a result, all samples exhibited a weight gain pattern, following a parabolic rate law showing diffusion-controlled oxide growth mechanism. P180 sample recorded the lowest parabolic rate constant, showing the lowest oxidation rate. In addition, P180 sample also displayed a uniform and incessant oxide layer without evidence of oxide exfoliation. [ABSTRACT FROM AUTHOR]