Water is omnipresent and is the foundation of all life on earth. However, the processes that take place at the molecular level in water are still not understood in every detail. Bernd Winter and colleagues from the Berlin electron storage ring BESSY and from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) were able to detect a hitherto unknown property of the negatively charged ion of the water, the hydroxide ion (OH-). They report on it in the prestigious scientific journal Nature (E.F. Aziz, N. Ottosson, M. Faubel, I. V. Hertel, and Winter, B., Nature, 455, 89-91, 2008).