An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder,and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captivebubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the effect of the nature. amount, size, and distribution of mineral inclusions in coal on its wettability are briefly reviewed.