Neoboletus luridiformis is a large solid fungus with a bay-brown hemispherical to convex cap that can grow up to wide, and is quite felty initially. It has small orange-red pores that become rusty with age, and bruise blue to black. The tubes are yellowish-green, and become blue quickly on cutting. The fat, colourful, densely red-dotted yellow stem is 4–12 cm (2–5 in) high, and has no network pattern (reticulation). The flesh stains dark blue when bruised; broken, or cut. There is little smell. The spore dust is olive greenish-brown.