A study of pool boiling from a commercial porous metallic matrix surface is reported. The excellent steady boiling characteristics of this type of surface are confirmed; however, high wall superheats are required in most cases to initiate boiling. The resultant boiling curve hysteresis does not appear to have been previously reported in the literature. This effect is indicated in recent pilot plant tests. The present results generally confirm the speculated mechanism of boiling with these surfaces and suggest reasons whereby single-tube performance may be superior to tube bundle performance.