One of the most important types of destruction is corrosion in high temperatures which consists of reactions of metal with gas or molten metal. Metal dusting is a reaction between metal and gas at temperatures up to 600 O C or higher that occurs in reformer tubes during exposing to a carbon contained gas and in direct iron-ore reduction industry. The aim of this study is to decrease metal destruction or to prevent reaction between metal and environment by applying suitable coatings. For this, the selective substrate was HP steel alloy which is used in reformer tubes. The cut sections from the mentioned alloy were coated by Cr 3 C 2 -NiCr coating using HVOF technique and then exposed to methane gas at 680 and 800 O C. The samples before and after deposition were evaluated using SEM, XRD and EDS techniques. The results showed significant decreases of graphite deposited through reducing diffusion of carbon in sample surface in both temperatures and also generation of stable chromium oxides, especially in 800 O C. Also it was found that the influence of coating in 680 °C was more than that of 800°c. The reduction of diffusion rate of carbon as a result of deposition in 680°c and 800°c was 30% and 10% respectively. Moreover, the substrate surface was protected by the coating which generates a protective and adhesive barrier. Keywords Metal dusting, Cr 3 C 2 -NiCr coating, HP, HVOF.