A 1-day x-ray diffraction experiment on DL-proline monohydrate was performed at 100 kelvin with synchrotron radiation and a charge-coupled device area detection technique. The accuracy of the charge density distribution and of the related electronic properties extracted from these data is comparable or even superior to the accuracy obtained from a 6-week experiment on DL-aspartic acid with conventional x-ray diffraction methods. A data acquisition time of 1 day is comparable to the time needed for an ab initio calculation on the isolated molecules, This technique renders larger molecular systems of biological importance accessible to charge density experiments.