The goal of this paper is to demonstrate that electrospray mass spectrometry when used with spectral libraries becomes a useful method for rapid identification of inorganic oxidizers commonly present in commercial and improvised explosives. Electrospray ionization mass spectra (ESI-MS) of oxidizers reveal a series of characteristic cluster ions. Such a set of cluster ions can be regarded as a "fingerprint" of a particular oxidizer. With the aid of a spectral library, tentative identification of inorganic oxidizer becomes automated and an easy-to-implement process. The oxidizer identity may be further confirmed by using tandem mass spectrometry (MS/MS). Because it is not necessary to separate the components before analysis, results become available in real time. Little sample consumption and the ease of sample preparation should also be noted. The methodology can be readily employed on various ESI-MS systems that are already in use in analytical laboratories. This is another important benefit as the ESI-MS instrumentation is becoming increasingly common in forensic laboratories.