Hastelloy X is a nickel-based superalloy, widely used in high temperature applications such as aircraft and land-based turbines. This technical paper deals with the high temperature erosion mechanisms and the surface roughness of Hastelloy X. The erosion mechanism of the Hastelloy X was studied using hot air jet erosion experiments at 800°C with varying parameters, like angle of impingement and erodent velocity. Characterization of the eroded samples was done using scanning electron microscopy (SEM) micrographs and high-resolution universal tribometer to determine the erosion mechanisms and surface roughness values. SEM micrographs of eroded samples reveal that lip formation, cutting, and ploughing are the dominant erosion mechanisms of Hastelloy X at a 45° angle of impingement, whereas, at 90°, it is lip extrusion followed by flattening of lip and detachment of platelet.