It has previously been reported that x-rays are emitted when adhesive tape is peeled in a vacuum but no account of the dependence of the x-ray emission on the pressure of the environment has been given to date. In this paper we present detailed experimental data on the number and angular distribution of x-ray photons as a function of pressure. We find that x-rays are emitted for pressures between p0 = 10−3 and p1 = 10−2 mBar, with ∼ 106 counts/(cm2 s) recorded by a 256×256 pixel2 silicon array sensor placed 35 mm from the tape. The main role of the tape is found to be the build-up of an acceleration potential sufficient to produce x-rays by bremsstrahlung of free electrons in a low-pressure gas. The source of the free electrons is the gas. Our model shows that the production rate of uncompensated tape charge and absorption of positive ions from the gas define p1. The angular distribution of the radiation shows a pressure-independent 20° wide peak in the direction perpendicular to electron motion. Ordinary bremsstrahlung cannot describe this peak.