The continuous development of the soft ionization technique is thought to have sparked the advancement of mass spectrometry (MS). Cold-spray ionization (CSI) has been adapted for analyses of various unstable organometallic complexes and biomolecules in solution. A combination of unique analytical capabilities, including CSI-MS, NMR and XRD has been developed to provide new insights about molecular interactions. CSI is designed for the mass spectrometric detection of labile organic species. It may be an appropriate method to analyze in solution the structure of bimolecular complexes, labile organic species including Grignard reagents, asymmetric catalysts, and supramolecules in solution. The method, a variant of ESI-MS, operating under low temperature, allows for a simple and precise characterization of labile noncovalent complexes that are difficult, or impossible, to observe by conventional ionization techniques. The principle of the CSI method and applications of the method in conjunction with other analytical techniques to a wide variety of labile organic species such, as molecular clusters, supramolecular polymers and host-guest complexes in solution, are presented. A new ionization method that uses metal-complex-based ionization probes to ionize large complex molecules, including biomacromolecules, are also shown.