Summary: We present a model for the description of growth and collapse of a vapor bubble in a small tube, and illustrate some typical results. It is found that the maximum volume of the bubble and its lifetime depend in a complex way on the channel geometry and the initial energy distribution. However, during most of the bubble’s lifetime, the internal pressure is very small, and the dynamics is mostly governed by the external pressure. The motivation for this work is offered by the possibiity to use vapor bubbles as actuators in fluid-handling microdevices.