A coffee capsule for placement in a group head of espresso-making machines may produce espresso like that made by baristas. The capsule has a body wall, a curved top with a circumferential strip of reduced thickness configured for puncture and a circular flange projecting outward from the bottom end of the body wall. The capsules seals tightly with the group head against water leakage and produces espresso of optimal extraction rate due to one or more of the following: the thickness of the flange, the proximal ridge and small step on the flange, the outer step adjacent the body wall projecting upward from the bottom end of the body wall In addition, the coffee capsule may be made of polypropylene copolymer TR-50 and preferably about 80% TR-50 to also facilitate sealing. The flange has a pre-welding diameter calculated to expand to about 37 mm after being welded to the lid.
