While structrual biology can give us static pictures of many metalloenzymes we often lack knowledge about the detailed movements of individual atoms/groups that are essential for the actual function. Pushing structural biology from frozen single snapshot of an enzyme towards recording “movies” while the enzyme is active, now becomes possible using femtosecond X-ray pulses from X-ray lasers. These allow to probe the active site of an enzyme at room temperature in a time resolved manner without the problems of radiation damage, that is an inherent problem for traditional X-ray studies of redox sensitive metalloenzymes. To observe intermediate states in a catalytic cycle proper reaction triggering and data collection strategies need to be developed. We will describe the development of a drop-on-demand sample delivery and reaction triggering system for XFELs capable of handling oxygen sensitive metalloenzymes and discuss applications of this approach to studies of several important metalloenzymes. These include mono-nuclear systems like isopeniclin N synthase, di-nuclear systems like methane monooxygenase and ribonucelotide reductase and systems containing more complex metal clusters, like NiFe hydrogenases. Combined time resolved X-ray spectroscopic and X-ray diffraction measurements on these systems enables a better understanding of the electronic and structural changes connected to the catalytic process in these enzymes and hence provides new insights about the specific reaction mechanisms.