HVOF-formed Cr3C2-NiCr cermet coatings are extensively utilized because of their remarkable resistance to wear and erosion degradation at both room temperature and specially elevated temperatures. This research focused on comparing feedstock powders, particularly nanocrystalline feedstock, and examining the wear and tribological behaviors of their HVOF-formed coatings at elevated temperatures. The experimental investigation included characterizing the Taber wear rates of the pre-oxidized coating samples, as well as the in situ tribometer friction behaviors of the coatings at 800 °C. The primary objective was to understand how the factors such as Cr3C2 particle size, nanocrystallinity, oxidation, and test conditions influence the sliding wear behaviors of the coatings assessed under Taber abrasive wear and tribometer conditions. Through detailed analyses of the tested samples using TGA, XRD, and SEM/EDXS techniques, mechanisms dominated by oxidation and abrasion are proposed to interpret the sliding wear results. A significant finding is that the smaller-sized powder containing nano- and submicron Cr3C2 particles significantly contributed to the improvement in abrasive wear resistance and the reduction of the friction coefficient at both room and high temperatures.