The circumstellar molecular envelope of HD 101584

CO radio line observations reveal a molecular gas envelope around the peculiar star HD101584 with characteristics very similar to those of wellknown young post-AGB objects. We estimate that there is at least 0.1 M of molecular gas, very likely remnant gas from a former AGB-envelope. This gas has been efficiently accelerated to very high velocities (>50 km s−1, and a significant fraction to >100 km s−1). There is evidence for an expanding disk-like structure seen close to edge-on, and a high-velocity bipolar outflow. In the latter the expansion velocity increases linearly with distance from the star, suggesting either a brief period of ejection or a fast wind interacting with a slower wind. A significant fraction of the high-velocity gas has reached a welldefined terminal velocity. Momentum well above the available radiation momentum has been transferred to the gas. There are also indications of highdensity, low-velocity molecular gas, possibly in a disk close to the star. The 12CO/13CO-ratio in the envelope is uncertain, but probably quite low (∼10). The systemic heliocentric velocity is 50±2 km s−1.