Bubbles of a mean diameter over 0.5×10^-3m to 20×10^-3m weregenerated in a water bath using a perforated nozzle. Attachment of the bubbles to acircular cylinder placed horizontally above the nozzle was observed with a stillcamera and a high-speed video camera. When the wettability of the cylinder wasgood, no bubbles attached to it. On the other hand, when the wettability waspoor, many bubbles attached to the cylinder and some of them were trapped on therear surface of the cylinder. The shape and size of the trapped bubbles just beforedetachment were determined as functions of the surface tension, contact angle, densities of liquid and gas based on an energy equation.