This letter describes a new strategy for initiating a chemical reaction that is based on the laser-inducedbreakdown of a nanoscopic barrier, which physically separates the reactants in space. Because the breakdownof the barrier is fast (∼0.3 μs) and owing to the nanometer dimension of the barrier, the reactants can bebrought together and the reaction can be initiated rapidly. The time scale most suited for this method (frommicroseconds to tens of milliseconds) bridges nicely between the faster time scales that are accessiblemostly with laser-based triggering experiments and the slower time scales that are studied most frequentlywith flow-based devices.